Process for Making Angstrom Scale and High Aspect Functional Platelets

ABSTRACT

A process for making functional or decorative flakes or platelets economically and at high production rates comprises applying a multi-layer sandwich of vapor deposited metal and release coats in alternating layers to a rotating chilled drum or suitable carrier medium contained in a vapor deposition chamber. The alternating metallized layers are applied by vapor deposition and the intervening release layers are preferably solvent soluble thermoplastic polymeric materials applied by vapor deposition sources contained in the vapor deposition chamber. The multi-layer sandwich built up in the vacuum chamber is removed from the drum or carrier and treated with a suitable organic solvent to dissolve the release coating from the metal in a stripping process that leaves the metal flakes essentially release coat free. The solvent and dissolved release material are then removed by centrifuging to produce a cake of concentrated flakes which can be air milled and let down in a preferred vehicle and further sized and homogenized for final use in inks, paints or coatings. In one embodiment the finished flakes comprise single-layer thin metal or metal alloy flakes or flakes of inorganic materials, and in another embodiment flakes are coated on both sides with protective polymeric coatings that were applied from suitable vacuum deposition sources or the like contained in the vapor deposition chamber.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a division of U.S. application Ser. No.10/758,985, filed Jan. 16, 2004, which is a division of U.S. applicationSer. No. 09/849,512, filed May 4, 2001, now U.S. Pat. No. 6,863,851,which is a continuation-in-part of application Ser. No. 09/425,514,filed Oct. 22, 1999, now U.S. Pat. No. 6,398,999, which claims priorityfrom U.S. Provisional Application No. 60/105,399, filed Oct. 23, 1998,all of which are incorporated herein by reference in their entireties.

FIELD OF THE INVENTION

This invention relates to a process for producing angstrom scale flakesor platelets that can be used for both functional and decorativeapplications. Some flakes produced by this process reach the nanoscalerange. The flakes can be metal, metal compounds, non-metal or clearflakes. Functional applications of the flakes include uses in protectivecoatings in which the flakes can add a level of rigidity to producecertain desired properties of the finished coating, or in which theflake layer can be used to screen out light of certain wave lengths toprotect an underlying pigmented layer. Reflective metal flakes areuseful in a variety of optical or decorative applications, includinginks, paints or coatings. Other uses of the flakes include microwave andelectrostatic applications, together with chemical process andbiological applications.

BACKGROUND

Conventional aluminum flake is manufactured in a ball mill containingsteel balls, aluminum metal, mineral spirits, and a fatty acid usuallystearic or oleic. The steel balls flatten the aluminum and break it intoflakes. When the ball milling is complete the slurry is passed through amesh screen for particle sizing. Flakes too large to pass through thescreen are returned to the ball mill for further processing. Flake ofthe proper size is passed through the screen and introduced to a filterpress where excess solvent is separated from the flake. The filter cakeis then let down with additional solvent. Such conventional aluminumflake typically has a particle size from about 2 to about 200 micronsand a particle thickness from about 0.1 to about 2.0 microns. Theseflakes are characterized by high diffuse reflectance, low specularreflectance, rough irregular flake micro surface, and a relatively lowaspect ratio.

Another process for making metal flakes is a process of Avery DennisonCorporation for making flakes sold under the designation Metalure. Inthis process both sides of a polyester carrier are gravure coated with asolvent-based resin solution. The dried coated web is then transportedto a metallizing facility where both sides of the coated sheet aremetallized by a thin film of vapor deposited aluminum. The sheet withthe thin metal film is then returned to the coating facility where bothsides of the aluminum are coated with a second film of the solvent-basedresin solution. The dried coated/metal sheet is then transported againto the metallizing facility to apply a second film of vapor depositedaluminum to both sides of the sheet. The resulting multi-layer sheet isthen transported for further processing to a facility where the coatingsare stripped from the carrier in a solvent such as acetone. Thestripping operation breaks the continuous layer into particles containedin a slurry. The solvent dissolves the polymer out from between themetal layers in the slurry. The slurry is then subjected to sonictreatment and centrifuging to remove the solvent and the dissolvedcoating, leaving a cake of concentrated aluminum flakes approximately65% solids. The cake is then let down in a suitable vehicle and furthersized by homogenizing into flakes of controlled size for use in inks,paints, and coatings. Metal flakes produced by this process for use inprintable applications such as inks are characterized by a particle sizefrom about 4 to 12 microns and a thickness from about 150 to about 250angstroms. Coatings made from these flakes have a high specularreflectance and a low diffuse reflectance. The flakes have a smoothmirror-like surface and a high aspect ratio. The coatings also have ahigh level of coverage per pound of flake applied when compared withmetal flakes produced by other processes.

Flakes also are produced in a polymer/metal vacuum deposition process inwhich thin layers of vapor deposited aluminum are formed on a thinplastic carrier sheet such as polyester or polypropylene, withintervening layers of cross-linked polymers between the vapor depositedaluminum layers. The cross-linked polymer layers are typically apolymerized acrylate deposited in the form of a vaporized acrylatemonomer. The multi-layer sheet material is ground into multi-layerflakes useful for their optical properties. Coatings produced from suchmulti-layer flakes tend to have a high diffuse reflectance and a lowspecular reflectance. The flakes have a low aspect ratio and undesiredlow opacity when made into an ink.

One objective of the present invention is to reduce the number ofmanufacturing steps and the resulting cost of making highly reflectivemetal flakes, although the process also reduces the coast of makingother flake-like materials described below.

In addition to metal flakes, there are many industrial uses of glass(SiO₂) flakes. Conventional glass flakes generally have a thicknessrange of about one to six microns and a diameter from about 30 to about100 microns. These glass flakes can be used for additions to polymersand coatings to improve various functional properties. These includeaddition of glass flakes as additives to produce thinner, smoothercoatings, for example. One objective of this invention is to producevery thin, flat, smooth flakes, such as metal or glass flakes, forexample, for use of their various functional properties in polymers,coatings and films.

SUMMARY OF THE INVENTION

The present invention comprises a flake forming process in which amulti-layer film is applied either to a thin, flexible polymeric carriersheet such as polyester, or to a polished metal casting surface such asa rotating metal drum. In either instance the process is carried out ina vacuum deposition chamber. In one embodiment, the multi-layer film isapplied to a polyester (PET) carrier sheet. The vacuum chamber isequipped with multiple deposition sources. The deposition sources can bevaporization at elevated temperatures caused by heating by resistance orEB. Air is evacuated from the chamber and the PET film is unwound pastthe coating and deposition sources while kept in contact with a coolingdrum. Alternating layers of materials can be applied to the moving PETweb. One example is an organic solvent-soluble vapor depositedthermoplastic polymeric release material (having a deposition thicknessof about 100 to about 400 angstroms), followed by a layer of metal suchas aluminum (having a deposition thickness of about 5 to about 500angstroms), followed by another layer of the solvent-soluble releasematerial. Other metals, metal alloys, or inorganic compounds for makingglass flakes, for example, may be substituted for the aluminum. Byreversing the web path and inactivating the second coating source andthen repeating the first step, many layers can be applied to the PETwithout breaking the vacuum, which can increase productivity. Additionalprotective layers can be deposited on each side of the metal layers byadding two additional deposition sources between the coating and metaldeposition sources. The multi-layered coated PET is introduced into anorganic solvent stripping process to remove the sandwich from the PET.The polymeric release coat material is dissolved by the organic solventto leave the deposited flake material essentially free of the releasematerial. The solvent is then centrifuged to produce a cake ofconcentrated flakes.

In an alternative embodiment, the same coating and deposition techniquesare used to apply alternating layers directly to a release coatedcooling drum contained in the vacuum deposition chamber. The drum isrotated past the coating and deposition sources to build up amulti-layer sandwich of vapor deposited thermoplastic release materialand flake material in alternating layers. The multi-layer sheet is thenintroduced directly into an organic solvent with or without suitableagitation to produce flakes; or it can be ground to rough flakes whichcan also be air-milled to further reduce particle size, and thenintroduced into a solvent slurry to allow the remaining layers to beseparated. The solvent may be removed by centrifuging to produce a cakeof concentrated metal flakes, essentially free of any release material.The cake of concentrated flakes or the slurry of solvent and flakes thencan be let down in a preferred vehicle and further sized and homogenizedfor final use in inks, paints, plastics or coatings.

Another embodiment of the invention comprises a process for making arelease-coated heat-resistant polymeric carrier sheet in the vacuumdeposition chamber. The carrier sheet can comprise a web of polyester(PET) as described above. The release coat comprises an organic solventsoluable thermoplastic polymeric material vapor deposited on thepolyester carrier. The release-coated carrier provides a flexible smoothsurfaced carrier base upon which to vapor deposit flake materials suchas metal or glass to provide an effective release surface for makingangstrom scale flakes. The flakes are exceedingly thin and flat whenreleased from the thermoplastic release coat via a suitable organicsolvent.

Other embodiments of the invention comprise techniques for controllingdelivery of the vapor deposited thermoplastic polymeric release coatmaterial to the vacuum chamber. These include a rotating drum, heaterblock and E-beam embodiment; several embodiments comprise a wire feedmechanism used to coat the polymer on a wire which is fed into thevacuum chamber and heated to evaporate the polymer and deposit it on arotating drum or other carrier surface.

Further embodiments comprise applications of the angstrom scaleparticles made by this invention which include flakes used to controlwater vapor transmission rates in barrier materials and electricalapplications in which the angstrom scale flakes can be used to produceconstructions having exceedingly high electrical capacitance.

These and other aspects of the invention will be more fully understoodby referring to the following detailed description and the accompanyingdrawings.

DRAWINGS

FIG. 1 is a schematic functional block diagram illustrating a prior artprocess for manufacturing metal flakes.

FIG. 2 is a schematic elevational view illustrating a vacuum depositionchamber for applying a multi-layer coating in a first embodiment of aprocess according to this invention.

FIG. 3 is a schematic cross-sectional view illustrating a sequence oflayers in one embodiment of the multi-layer sheet material according tothis invention.

FIG. 4 is a schematic cross-sectional view illustrating a multi-layersheet material made according to another embodiment of this invention.

FIG. 5 is a functional block diagram schematically illustratingprocessing steps in the first embodiment of this invention.

FIG. 6 is a schematic cross-sectional view illustrating single layerflakes made by the process of this invention.

FIG. 7 is a schematic cross-sectional view of multi-layer flakes made bythe process of this invention.

FIG. 8 is a schematic elevational view illustrating a second embodimentfor producing the metal flakes of this invention.

FIG. 9 is a functional block diagram schematically illustratingprocessing steps for making flakes from the multi-layer material madeaccording to the second embodiment of the invention.

FIG. 10 is a semi-schematic elevational view illustrating a bell jarvacuum chamber.

FIG. 11 is a semi-schematic side elevational view showing a vacuumchamber containing a rotating drum and heater block assembly.

FIG. 12 is a side elevational view of a rotating drum and heated polymervapor chamber shown in FIG. 11.

FIG. 13 is a semi-schematic side elevational view showing vacuum chamberand heater block assembly similar to FIGS. 11 and 12 in combination witha wire feed apparatus for delivering polymeric release coat material toa rotating drum surface in the vacuum chamber.

FIG. 14 is a side elevational view of the rotating drum and heater blockassembly illustrated in FIG. 13.

FIG. 15 is one embodiment of a wire feed mechanism and vapor tubecombination for delivering polymer release coat material to a vacuumchamber.

FIG. 16 is a side elevational view of a heated polymer vapor tube androtating drum shown in FIG. 15.

FIGS. 15A and 16A are alternative embodiments of the wire feed mechanismshown in FIGS. 15 and 16;

FIG. 17 is a semi-schematic side elevational view illustrating a heatedmelt tube apparatus for delivering polymeric base coat material to avacuum chamber.

FIG. 18 is a side elevational view showing a heated polymer vapor tubeand rotating drum illustrated in FIG. 17.

FIG. 19 is a semi-schematic side elevational view illustrating a processfor making carrier sheet material with a polymeric release coataccording to principles of this invention.

FIG. 20 is a semi-schematic elevational view showing a melt pump processfor delivering polymer release material to a vacuum chamber.

DETAILED DESCRIPTION

In order to better appreciate certain aspects of this invention,reference is made to FIG. 1 which illustrates a prior art process formaking metal flakes according to a process presently utilized by AveryDennison Corporation for manufacturing flakes sold under the designationMetalure.

According to this prior art process, both sides of a polyester carriersheet 10 are gravure coated at 12 with a solvent-based resin solution14. The dried coated web is then transported to a metallizing facility16 where both sides of the coated and dried carrier sheet are metallizedwith a thin film of vapor deposited aluminum. The resulting multi-layersheet is then transported for further processing to a facility at 18where the coatings are stripped from the carrier in a solvent such asacetone to form a solvent-based slurry 20 that dissolves the coatingfrom the flakes. The slurry is then subjected to sonic treatment andcentrifuging to remove the acetone and dissolved coating, leaving a cake22 of concentrated aluminum flakes. The flakes are then let down in asolvent and subjected to particle size control at 24 such as byhomogenizing.

This process has proved highly successful in producing extremely thinmetal flakes of high aspect ratio and high specular reflectance. (Aspectratio is the ratio of average particle size divided by average particlethickness.) Despite the success of the Metalure process, it would bedesirable to reduce production costs because the repeated transportationof the coated web between gravure coating and metallizing facilitiesincreases the cost of production. There is also a production costassociated with the PET carrier not being reusable after the strippingoperations.

FIGS. 2 to 5 illustrate one embodiment of a process for making the metalflakes shown in FIGS. 6 and 7. This process also can be used for makingglass flakes, described below, and also can be used for makingnanospheres, as described below. FIG. 2 illustrates a vacuum depositionchamber 30 which contains suitable coating and metallizing equipment formaking the multi-layer coated flakes 32 of FIG. 7. Alternatively,certain coating equipment in the vacuum chamber of FIG. 2 can bedeactivated for making the single layer flakes 34 of FIG. 6, as willbecome apparent from the description to follow.

Referring again to FIG. 2, the vacuum deposition chamber 30 includes avacuum source (not shown) used conventionally for evacuating suchdeposition chambers. Preferably, the vacuum chamber also will include anauxiliary turbo pump (not shown) for holding the vacuum at necessarylevels within the chamber without breaking the vacuum. The chamber alsoincludes a chilled polished metal drum 36 on which a multi-layersandwich 38 is produced. This embodiment of the invention will first bedescribed with reference to making the flakes 32 of FIG. 7 which, in oneembodiment, includes an internal metallized film layer 40 and outerlayers 42 of a protective coating bonded to both sides of the metalfilm. The protective coating can comprise an inorganic material or apolymeric material, both of which are vapor deposited under vacuum.

The vacuum deposition chamber includes suitable coating and vapordeposition sources circumferentially spaced apart around the drum forapplying to the drum a solvent soluble or dissolvable release coating, aprotective outer coating, metal layer, a further protective outercoating for the metal layer, and a further release layer, in that order.More specifically, these sources of coating and deposition equipmentcontained within the vacuum deposition chamber include (with referenceto FIG. 2) a release system source 44, a first protective coating source46, a metallizing source 48, and a second protective coating source 50.These coating and/or deposition sources are spaced circumferentiallyaround the rotating drum so that as the drum rotates, thin layers can bebuilt up to form the multi-layered coating sandwich 36 such as, forexample, in sequence:release-coating-metal-coating-release-coating-metal-coating-release, andso on. This sequence of layers built up in the multi-layer sandwich 38is illustrated schematically in FIG. 4 which also illustrates the drum36 as the carrier in that instance.

In one embodiment, the release coating is either solvent-soluble ordissolvable but is capable of being laid down as a smooth uniformbarrier layer that separates the metal or glass flake layers from eachother, provides a smooth surface for depositing the intervening metal orglass flake layers, and can be separated such as by dissolving it whenlater separating the metal or glass flake layers from each other. Therelease coating is a dissolvable thermoplastic polymeric material havinga glass transition temperature (T_(g)) or resistance to melting that issufficiently high so that the heat of condensation of the depositedmetal layer (or other flake layer) will not melt the previouslydeposited release layer. The release coating must withstand the ambientheat within the vacuum chamber in addition to the heat of condensationof the vaporized metal or glass flake layer. The release coating isapplied in layers to interleave various materials and stacks ofmaterials so as to allow them to be later separated by solubilizing therelease layer. A release layer as thin as possible is desired because itis easier to dissolve and leaves less residue in the final product.Compatibility with various printing and paint systems also is desirable.The release coating is solvent-soluble, preferably a thermoplasticpolymer, which is dissolvable in an organic solvent. Although therelease coating source 44 can comprise suitable coating equipment forapplying the polymeric material as a hot melt layer or for extruding therelease coat polymer directly onto the drum, in the preferredembodiment, the release coat equipment comprises a vapor depositionsource that vaporizes a suitable monomer or polymer and deposits it onthe drum or sandwich layer. Various examples of vapor depositionequipment for applying the polymeric release coat to the depositionsurface are described below. The release material freezes to solidifywhen it contacts either the chilled drum or the multi-layer sandwichpreviously built up on the chilled drum. The multi-layer film built upon the drum has a thickness sufficient to enable the chilled drum topull enough heat through the film so as to be effective in solidifyingthe release coat being deposited on the outer surface of the metal orglass flake layer. An alternative polymeric release coating material canbe lightly cross-linked polymeric coatings which, while not soluble,will swell in a suitable solvent and separate from the metal or glassflake material. In addition, a dissolvable release material may comprisea polymeric material which has been polymerized by chain extensionrather than by cross-linking.

Presently preferred polymeric release coatings are styrene polymers,acrylic resins or blends thereof. Cellulosics may be suitable releasematerials, if capable of being coated or evaporated withoutdetrimentally affecting the release properties.

Presently preferred organic solvents for dissolving the polymericrelease layer include acetone, ethyl acetate and toluene.

Referring again to the process of making the flakes shown in FIG. 2, andfollowing application of the release coating, the drum travels past thefirst protective coating source 46 for applying a protective layer tothe release coat. This protective layer can be a vapor depositedfunctional monomer such as an acrylate or methacrylate material which isthen cured by EB radiation or the like for cross-linking or polymerizingthe coating material; or the protective material can be a thin layer ofradiation cured polymer which can be later broken up into flakes.Alternatively, the protective layer can be a vapor deposited inert,insoluble inorganic or glass flake material which forms a hard clearcoat that bonds to both sides of the metal layer. Desirable protectivecoatings are hard impervious materials which can be deposited inalternating layers with metals such as aluminum to provide a level ofwear resistance, weatherability protection, and water and acidresistance. Examples of such protective materials are described below.

The rotating drum then transports the coating past the metallizingsource 48 for vapor depositing a layer of metal such as aluminum on thecoating layer. A number of metals or inorganic compounds can bedeposited as a thin film interleaved by other materials and releaselayers so they can be later separated into thin metallic flakes. Inaddition to aluminum, such materials include copper, silver, chromium,nichrome, tin, zinc, indium, and zinc sulfide. Metal coatings also caninclude multi-directional reflection enhancing stacks (layers of highlyreflective materials), or optical filters made by depositing suitablelayers of controlled thickness and index of refraction.

The rotating drum then transports the stack past the second coatingsource 50 for again applying a similar protective coating layer to themetallized film such as by vapor deposition and curing of a hardprotective polymeric material or vapor depositing an inorganic material.

Rotation of the drum then transports the sandwich material full circleagain past the release coat source and so on in sequence to build up thecoated metal layers.

Inorganic materials such as oxides and fluorides also can be vapordeposited by the deposition source 48 so as to produce thin layers thatcan be separated and made into flakes. Such coatings include magnesiumfluoride, silicon monoxide, silicon dioxide, aluminum oxide, aluminumfluoride, indium tin oxide and titanium dioxide.

Suitable deposition sources include EB, resistance, sputtering andplasma deposition techniques for vapor depositing thin coatings ofmetals, inorganics, glass flake material and polymers.

Once the multi-layer sandwich is produced in the vacuum depositionchamber, it is then ready to be removed from the drum and subjected tofurther processing illustrated in FIG. 5.

The continuous process of building up the multi-layer sandwich isdepicted at FIG. 52 in FIG. 5. The multi-layer sandwich is then strippedfrom the drum at 54 by a process in which the layers that are separatedby the releasing material are broken apart into individual layers. Thesandwich layers may be stripped by introducing them directly into anorganic solvent, or by crushing and grinding or scraping. In theillustrated embodiment, the multi-layer sandwich is subjected togrinding at 56 to produce rough flakes 58. The rough flakes are thenmixed with a suitable solvent in a slurry 60 for dissolving the releasecoat material from the surfaces of the multi-layer flakes 32.Alternatively, the multi-layer sandwich may be stripped from the drumand broken into individual layers by a step 63 of introducing thelayered material directly into the solvent at 60. The release coatmaterial applied in the vacuum deposition chamber is selected so thatthe release material is dissolvable from the flakes by the solvent inthe slurry process. In one embodiment, the slurry is subjected to acentrifuging step 61 so that the solvent or water is removed to producea cake of concentrated flakes. The cake of concentrated flakes then canbe let down in a preferred vehicle, in a particle size control step 62,to be further sized and homogenized for final use of the flakes in inks,paints or coatings, for example. Alternatively, the flakes can be letdown in a solvent (without centrifuging) and subjected to particle sizecontrol at 62.

As an alternative processing technique, the multi-layer sandwich can beremoved from the drum and “air” milled (inert gas should be used toprevent fire or explosion) or otherwise reduced to a small particlesize, followed by treating this material in a two-step solvent process.First a small amount of solvent is used to begin the swelling process indissolving the release coat layers. A different second solvent is thenadded as a finished solvent for completing the release coat dissolvingprocess and for enhancing compatibility with the finished ink orcoating. This process avoids subsequent centrifuging and homogenizationsteps.

In an alternative embodiment for utilizing the vacuum chamber 30equipment of FIG. 2 the protective coating sources 46 and 50 can beomitted and the process can be used for making the single layer flakes34 shown in FIG. 6. In this instance the build up of layers on the drum36 to form the multi-layer sandwich 38 comprises successive layers ofrelease-metal-release-metal-release, and so on, as illustrated at 64 inFIG. 3. Alternatively, the single layer flakes can comprise layers of aninorganic or glass flake material as described above.

Many different materials and stacks of materials can be constructedwhere they are sandwiched by the soluble release layers that allow themto be separated from each other by solubilizing the release material.Examples of such constructions are: (1) release/metal/release; (2)release/protective layer/metal/protective layer/release; (3)release/nonmetal layer/release; and (4) release/multi-directionalreflection enhancing stack/release.

FIGS. 8 and 9 illustrate an alternative process for making the flakesillustrated in FIG. 6 or 7. In the embodiment illustrated in FIG. 8, theprocess equipment comprises a vapor deposition chamber 66 which containsa chilled rotating drum 68 and a flexible insoluble polyester carrierfilm 70 extending from a first reversible winding station 72 around alength of the drum's surface to a second reversible winding station 73.The length of wrap on the drum is controlled by two idle rollers 74.This vacuum chamber also includes the standard vacuum pump and anauxiliary turbo pump to maintain the vacuum level during coatingoperations. Rotation of the drum causes the polyester film to travelpast a first release coat source 76, a first protective coating source78, a metallizing source 80, a second protective coating source 82 and asecond release coat source 84, in that order. Thus, as the drum rotatesin a counterclockwise direction with respect to FIG. 8 the entire lengthof the polyester carrier is unwrapped from station 72 and taken up onstation 73 after passing through the coating processes in sequence fromsources 76, 78, 80, 82 and 84. The polyester carrier is then rewound byreversing the web path and inactivating the second release coatingsource 84 and then repeating the first step, but in a reverse(clockwise) direction so that the coatings are next applied from sources82, 80, 78 and 76, in that order. The entire PET coated film is thentaken up on station 72 and the sequence of steps is then repeated tobuild up layers on the film in the same sequence used to produce themulti-layer sandwich 38 of FIG. 4 (and the resulting coated metal flakes32 of FIG. 7).

Alternatively, in the instance in which the single layer metal or glassflakes of FIG. 6 are to be produced, the multi-layer sandwich 64illustrated in FIG. 3 is built up on the polyester carrier 70 byinactivating the protective coating sources 78 and 82.

FIG. 9 illustrates processing of the multi-layered coating sandwich 86built up on the polyester film which is removed from the vacuum chamber66 and introduced into an organic solvent stripping process at 88 toremove the sandwich material from the PET. The solvent is then subjectedto centrifuging to produce a cake 90 of concentrated flakes which islater subjected to particle size control (homogenizing) at 92.

Suitable carriers on which the multi-layer sandwich material may bedeposited must ensure that the deposits of thin layers are smooth andflat. Polyester films or other polymeric films having a high tensilestrength and resistance to high temperature can be used, along withmetal drums, belts or plates which can be stainless steel or chromeplated.

In one embodiment of the invention, polymeric release coats are appliedfor the purpose of facilitating later separation of the flake layersbuilt up in the multi-layer sandwich material. Prior art use ofcross-linked polymeric layers bonded between vapor deposited metallayers in a polymer/metal vapor deposition process inhibits laterseparation of the metallized layers into flakes. Polymerization of thepolymeric layers such as by EB curing prevents subsequent re-dissolvingof the polymeric layers and so the aluminum flake layers do not easilycome apart. In the present process, the intervening polymeric layers arevaporized and deposited while under vacuum in the vacuum depositionchamber. The polymeric release material is preferably a flowable lowviscosity, relatively low molecular weight very clean thermoplasticpolymer or monomer which is essentially free of any volatiles that wouldbe evolved during the coating process. Such a material is preferably nota blend of different polymeric materials including additives, solventsand the like. When the polymeric material is heated to its melt orcoating or deposition temperature, continuous operation of the vacuumpump in the vacuum chamber is not adversely affected by volatiles. Thepreferred release coat material promotes intercoat separation betweenalternating vacuum deposited metal or glass flake or multi-layer flakelayers. The release layer accomplishes this objective by beingdissolvable in a suitable organic solvent. The release material also ismetallizable and also requires sufficient adhesion to enable stackbuild-up on a rotating drum, as well as being EB vaporizable. Thedesirable release coat material must have a sufficiently high molecularweight or resistance to melting such that it resists heat build up onthe drum or other carrier without becoming flowable. Heat build up comesnot only from the metal deposited on the release layer but also fromoperation of the deposition sources inside the chamber. The ability ofthe release coat to resist flowability can ensure that flakes with highbrightness can be produced because the release coat surface on whichmetal is deposited remains smooth. The release material also must be onewhich can survive the heat of EB deposition. It must also not be amaterial, such as certain low molecular weight materials, whichdetrimentally affects vacuum pressure maintained in the chamber, say becausing the chamber to lose vacuum. Maintaining a minimum operatingvacuum level in the chamber is required to maintain production speedwithout breaking the vacuum. During subsequent stripping and treatmentwith organic solvents, essentially all of the release coat material isremoved from the flakes. However, in the event that some small amount ofrelease coat material may remain on the flakes after the flake layersare broken down into particles, the system can withstand some residuefrom the release coat, particularly if the flakes are subsequently usedin acrylic inks or paints or coating systems in which the flakes arecompatible.

Referring to the embodiment of FIG. 2, the multi-layer sandwich is madeby applying the coatings directly to the rotating drum, and this is adesirable process because it has lower production costs than the processof coating a PET carrier. Each such cycle involves breaking the vacuum,taking out the sandwich layer for further processing outside the vacuumchamber, and re-charging the vacuum. The rate at which the process canbe run, in building up layers, can vary from approximately 500 to 2,000feet per minute. Metallizing only in the vacuum can operate at higherspeeds.

In the embodiments in which the single layer flakes are produced, theflakes can have high aspect ratios. This is attributed, in part, to thecapability of cleanly removing the intervening release coat layers fromthe metallized flakes. With thermoset or cross-linked polymeric layersbonded in between the metal layers, the layers cannot be easilyseparated and resulting flakes have lower aspect ratios. In oneembodiment, the process of this invention produces single layerreflective aluminum flakes approximately 5 to 500 angstroms thick, andapproximately 4 to 12 microns in particle size.

The release coat materials are applied in exceedingly thin layerspreferably about 0.1 to about 0.2 microns for coated layers and about100 to 400 angstroms for EB deposited layers.

In the embodiments in which the metal flakes are coated on oppositesides with the protective polymeric film layers, the protective coatinglayers are applied at a thickness of about 150 angstroms or less. Apreferred protective coating material is silicon dioxide or siliconmonoxide and possibly aluminum oxide. Other protective coatings caninclude aluminum fluoride, magnesium fluoride, indium tin oxide, indiumoxide, calcium fluoride, titanium oxide and sodium aluminum fluoride. Apreferred protective coating is one which is compatible with the ink orcoating system in which the flakes are ultimately used. Use of theprotective coatings on the metal flakes will reduce aspect ratio of thefinished flake product, although the aspect ratio of this multi-layerflake is still higher than the ratio for conventional flakes. However,such flakes are more rigid than the single layer flakes, and thisrigidity provided by the clear glass-like coated metal flakes can, insome instances, make the coated flakes useful in fluidized bed chemicalvapor deposition (CVD) processes for applying certain optical orfunctional coatings directly to the flakes. OVD coatings are an example.CVD coatings can be added to the flakes for preventing the flakes frombeing prone to attack by other chemicals or water. Colored flakes alsocan be produced, such as flakes coated with gold or iron oxide. Otheruses for the coated flakes are in moisture-resistant flakes in which themetal flakes are encapsulated in an outer protective coat, and inmicro-wave active applications in which an encapsulating outer coatinhibits arcing from the metal flakes. The flakes also can be used inelectrostatic coatings.

In an alternative embodiment there may be instances in which the releasecoat layers comprise certain cross-linked resinous materials such as anacrylic monomer cross-linked to a solid by UV or EB curing. In thisinstance the multi-layer sandwich is removed from the drum, or while onthe carrier, it is treated with certain materials that de-polymerize therelease coat layers such as by breaking the chemical bonds formed fromthe cross-linking material. This proces allows use of conventionalequipment utilizing vapor deposition and curing with EB or plasmatechniques.

The process of this invention enables production of reflective flakes athigh production speeds and low cost. The uncoated flakes produced bythis invention can have a high aspect ratio. Where aspect ratio isdefined as the ratio of particle size to thickness, and the averageflake size is approximately 6 microns by 200 Angstroms (onemicron=10,000 Angstroms) the aspect ratio 60,000/200 is or about 300:1.This high aspect ratio is comparable to the Metalure flakes describedpreviously. For the embodiments in which flakes are coated on both sideswith protective layers, the aspect ratio of these flakes isapproximately, 60,000/600 or about 100:1.

Embossed flake also can be made by the process of this invention. Inthis instance, the carrier or deposition surface (drum or polyestercarrier) can be embossed with a holographic or diffraction gratingpattern, or the like. The first release layer will replicate thepattern, and subsequent metal or other layers and intervening releaselayers will replicate the same pattern. The stack can be stripped andbroken into embossed flakes.

One process for speeding production of the flake products made by thisinvention utilizes three side-by-side vacuum chambers separated by airlocks. The middle chamber contains a drum and the necessary depositionequipment for applying the layers of flake material and release coats tothe drum. When the deposition cycle is completed, the drum and coatingare transferred to the vacuum chamber downstream from the depositionchamber, through the air lock, for maintaining the vacuum in bothchambers. The middle chamber is then sealed off. A drum contained in theupstream chamber is then moved to the middle chamber for furtherdeposition. This drum is moved through an air lock to maintain thevacuum in both chambers. The middle chamber is then sealed off. Thecoated drum in the downstream chamber is removed, stripped of itsdeposited layers, cleaned and replaced in the upstream chamber. Thisprocess enables continuous coating in the middle vacuum chamber withoutbreaking its vacuum.

Example 1

The following multi-layer construction was made: releaselayer/metal/release layer. The release layer was Dow 685D extrusiongrade styrene resin and the metal layer was aluminum from MaterialsResearch Corp. 90101E-AL000-3002.

The construction was repeated 50 times, i.e., alternating layers ofaluminum and styrene release coats.

The styrene used in the release layer was conditioned as follows:

-   -   The styrene pellets were melted and conditioned in a vacuum oven        at 210° C. for 16 hours and then removed to a desiccator to        cool.    -   An aluminum foil lined graphite crucible was used to hold this        material.    -   This crucible was placed in a copper lined Arco    -   Temiscal single pocket electron beam gun hearth.

The aluminum pellets were melted into a copper lined

Arco Temiscal four-pocket electron beam gun hearth.

The electron beam guns were part of a 15 KV Arco Temiscal 3200 load-locksystem. Two mil PET film from SKC was cut into three seventeen inchdiameter circles and attached to seventeen inch diameter stainless steelplanetary discs located in the vacuum chamber. The chamber was closedand roughed to ten microns then cryopumped to a vacuum of 5×10-7 Torr.

The release and metal material were vapor deposited in alternatinglayers. The release layer was deposited first at 200 angstroms asmeasured by a Inficon IC/5 deposition controller. The release layer wasfollowed by a metal layer vapor deposited at 160 angstroms also measuredby the IC/5 controller. The controller for the aluminum layer wascalibrated by a MacBeth TR927 transmission densitometer with greenfilter. As mentioned, this construction was repeated 50 times. The vapordeposited aluminum layer had a good thickness of 1.8 to 2.8 opticaldensity as measured by a MacBeth densitometer. This value measures metalfilm opacity, via a light transmission reading.

When the deposition was complete, the chamber was vented with nitrogento ambient pressure and the PET discs removed. The discs were washedwith ethyl acetate then homogenized using a IKA Ultra Turrax T45 toreach a particle size of 3 by 2 microns, measured on Image-pro plusimage analyzer using a 20× objective and averaged from a set of 400particles.

The dispersion was then made into an ink and drawn down on a Lenettacard for ACS spectrophotometer testing. This test measures flakebrightness. An ACS value above about 68 is considered desirable for thisparticular product. ACS readings were 69.98 for the Metalure control and70.56 for the batch. The inks were drawn down on clear polyester anddensity readings were 0.94 for the batch and 0.65 for the Metalurecontrol. Readings were taken on a MacBeth densitometer using a greenfilter.

Example 2

The following multi-layer construction was made: releaselayer/protective coat/metal/protective coat/release layer.

Three separate constructions were made as follows:

Construction 1

-   -   REL Dow 685D    -   PROT Cerac Silicon Oxide S-1065    -   MET Materials Research Corp. 90101E-AL000-3002    -   PROT Cerac Silicon Oxide S-1065    -   REL Dow 685D

Construction 2

-   -   REL Dow 685D    -   PROT Cerac Aluminum Oxide A-1230    -   MET Materials Research Corp. 90101E-AL000-3002    -   PROT Cerac Aluminum Oxide A-1230    -   REL Dow 685D

Construction 3

-   -   REL Dow 685D    -   PROT Cerac Magnesium Fluoride M-2010    -   MET Materials Research Corp. 90101E-AL000-3002    -   PROT Cerac Magnesium Fluoride M-2010    -   REL Dow 685D

The construction were repeated ten times by the same process describe inExample 1 and were evaluated as protective coated flake, i.e., this testindicated that multi-layer flakes having optical utility could be madeby building up the layers of flake material on a carrier in a vacuumchamber between intervening layers of dissolvable release material, inwhich the flake layers are built up continuously (without breaking thevacuum) while depositing the release layers and flake layers fromdeposition sources operated within the vacuum chamber, followed bystripping, and particle size control.

Example 3

The following multi-layer constructions were made:

Construction 1

-   -   REL Dow 685D    -   NONMET Silicon Oxide S-1065    -   REL Dow 685D

Construction 2

-   -   REL Dow 685D    -   Stack Titanium Dioxide Cerac T-2051    -   Stack Silicon Oxide Cerac S-1065+Oxygen    -   MET Materials Research Corp. 90101E-AL000-3002    -   Stack Silicon Oxide Cerac S-1065+Oxygen    -   Stack Titanium Dioxide Cerac T-2051    -   REL Dow 685D

The construction was repeated ten time by the same process described inExample 1. This test indicated that the process of vapor deposition canform built-up layers of optical stacks between intervening release coatlayers in a vacuum chamber, followed by stripping and particle sizecontrol, which yielded flakes having utility for such applications asinks and coatings.

Example 4

The following constructions may be possible constructions for decorativeflake:

Construction 1

-   -   REL Dow 685D    -   Stack Iron Oxide Cerac 1-1074    -   Stack Silicon Oxide Cerac S-1065+Oxygen    -   Stack Iron Oxide Cerac 1-1074    -   REL Dow 685D

Construction 2

-   -   REL Dow 685D    -   Stack Iron Oxide Cerac 1-1074    -   Stack Silicon Oxide Cerac S-1065+Oxygen    -   MET Aluminum Materials Research Corp. 90101E-AL000-3002    -   Stack Silicon Oxide Cerac S-1065+Oxygen    -   Stack Iron Oxide Cerac 1-1074    -   REL Dow 685D

The constructions also may be used for a gonio chromatic shift.

Example 5

Polymeric release coat layers were deposited in a vacuum chamber, usingan EB source, and coated with a vapor deposited aluminum layer.

The following constructions were made:

Construction 1

Dow 685D styrene resin was conditioned in an oven for 16 hours at 210°C. The material was EB deposited on polyester at a thickness of 200 to400 angstroms and metallized with one layer of aluminum at densities of2.1 to 2.8.

Construction 2

Piolite AC styrene/acrylate from Goodyear was conditioned for 16 hoursat 190° C. The material was EB deposited on polyester at a coat weightof 305 angstroms metallized with one layer of aluminum at a density of2.6.

Construction 3

BR-80 acrylic copolymer from Dianol America was conditioned for 16 hoursat 130° C. The material was EB deposited on polyester at a thickness of305 angstroms metallized with one layer of aluminum at a density of 2.6.

Construction 4

Dow 685D styrene resin was conditioned for 16 hours at 210° C. Thematerial was EB deposited on polyester at a thickness of 200 angstromsand metallized with one layer of aluminum at a density of 2.3. This wasrepeated to form a stack of 10 layers of aluminum separated by theintervening release coat layers.

These layered materials were stripped from the PET carriers using ethylacetate solvent and reduced to a controlled particle size in a T8 labhomogenizer. The resulting flakes were similar in optical properties toMetalure flakes, in that they had similar brightness, particle size,opacity and aspect ratio.

In a further test with a construction similar to Construction 1,aluminum metallized to an optical density of 2.3 was stripped from a PETcarrier in acetone and broken into flakes. This test observed the effectof release coat thickness changes. The results indicated best releaseproperties with an EB deposited release coat in the range of about 200to about 400 angstroms.

Example 6

Several tests were conducted to determine various polymeric release coatmaterials that may be useful in this invention. Laboratory Bell Jartests were conducted to determine polymers that may be EB deposited.Methyl methacrylate (ICI's Elvacite 2010) and a UV-cured monomer(39053-23-4 from Allied Signal) produced good results. Poor results wereobserved with butyl methacrylate (Elvacite 2044) (loses vacuum in EB),cellulose (turned black at 280° F.), and polystyrene rubber (charred).

Example 7

The tests described in Example 1 showed that a release coat made fromthe Dow 685D styrene polymer could produce usable flake products.Several other tests were conducted with Dow 685D styrene resin releasecoats as follows:

(1) Conditioned at 190° C., coated at 1,000 angstroms and metallizedwith aluminum. Resin film built too high produced a hazy metallizedlayer.

(2) Not conditioned in oven; when attempting to EB melt the styrenebeads the E-Beam caused the beads to move in the crucible.

(3) Conditioned at 210° C., coated from 75 to 150 angstroms thenmetallized. Aluminum stripped poorly or not at all.

(4) Conditioned at 210° C., coated at 600 angstroms and metallized onelayer of aluminum at 1.9 density. Aluminum stripped slowly and produceda curled flake.

This invention makes it possible to produce thin decorative andfunctional platelets of single or multilayer materials with thicknessfrom about 5 to about 500 angstroms single layer, from about 10 to 2000angstroms multilayer, with average outer dimensions from about 0.01 to150 micrometers. The flakes or particles made by the process of thisinvention are referred to as angstrom scale particles because they areuseful flake material that can be made with a thickness in the lowangstrom range mentioned above. Some particles made by this inventioncan be characterized as nanoscale particles. As is well known, 10angstroms equals one nanometer (nm), and the nanoscale range isgenerally from one to 100 nm. Thus, some of the angstrom scale particles(thickness and/or particle size) of this invention fall within thenanoscale range.

These particles can be used as functional platforms by themselves orcoated with other active materials. They can be incorporated into orcoated onto other materials. As mentioned above, they are produced bydepositing materials or layers of materials such that the mono ormultilayered platelets are interleaved with polymeric releasing layers.The supporting system for these layer sandwiches can be a plate, film,belt, or drum. The functional materials can be applied by PVD (physicalvapor deposition) processes and the releasing layers can be applied byPVD.

Once the sandwich layers with the interleaving releasing layers areformed the material can be removed from the supporting system andfunctional layers can be separated from the releasing layers. This canbe done cryogenically, with the appropriate solvent, or with asupercritical fluid. The resulting material can be turned into plateletsand sized by grinding, homogenizing, sonolating, or high-pressureimpingement.

Centrifuging or filtering results in a cake, slurry, or dried material.Other active materials can be added to the particles via CVD or reactedwith materials such as silanes to promote adhesion. Then the materialscan then be incorporated into or coated onto the desired material suchas paints, coatings, inks, polymers, solids, solutions, films, fabrics,or gels, for functional uses.

Various angstrom scale flake constructions of this invention include (1)aluminum, metal alloy and other metal (described below) monolayerflakes; (2) single layer dielectrics, inorganic or cross-linked polymerflakes; (3) multi-layer inorganics; (4) optical stacks; (5) inorganic ororganic/metal/inorganic or organic multilayer flakes; (6)metal/inorganic/metal flakes/and (7) CVD or chemically reacted surfacecoated flakes.

The uses for these nanoscale and high aspect ratio particles are asfollows.

Optical Aesthetic

High aspect ratio materials can provide bright metallic effects as wellas colored effects. Metals such as aluminum, silver, gold, indium,copper, chromium or alloys and metal combinations such as aluminumcopper, copper zinc silver, chromium nickel silver, titanium nitride,titanium zirconium nitride and zirconium nitride may be used to producethese materials. Sandwiches of metals and dielectric materials canproduce various colors and effects. Inert materials can be used as theoutside layer to protect the inner layers from oxidation and corrosion.Examples of some sandwiches are SiO/Al/SiO, MgF/Al/MgF, Al/SiO/Al,Al/MgF/Al, but many other combinations are possible. Flakes of metal ormetal oxides can be used as a base to attach both organic and inorganicmaterials that provide pigment-like colors.

Optical Functional

Nanoscale and high aspect ratio particles can have many applicationsthat take advantage of optical properties. Particles of aluminum oxide,titanium dioxide, zinc oxide, indium tin oxide, indium oxide can beincorporated into coatings and polymers to reflect, scatter, or absorbUV and IR light. Also phosphorescent and fluorescent materials can beused to produce other important effects.

Mechanical

These particles can be incorporated into or applied to the surface ofmaterials to enhance their properties. Particles of silicon monoxide,aluminum dioxide, titanium dioxide, and other dielectrics can beincorporated into materials to improve properties such as flameretardancy, dimensional stability, wear and abrasion resistance,moisture vapor transmission, chemical resistance, and stiffness.

Chemical

Active materials can be applied to the surface of these particles toprovide small high surface areas that can be introduced into chemicalprocesses. These high surface area particles are ideal for catalysts.They can be platelets of the active material or flakes made to supportan active coating. Examples of active materials are platinum, palladium,zinc oxide, titanium dioxide, and silicon monoxide. Flakes produced frommetal (lithium) doped materials may have uses in batteries.

Electrical

Electrical properties can be imparted to various materials and coatingsby incorporating particles of various materials as both monolayers andmultilayers to effect conductivity, capacitance, EMI, and RFI. Theabsorption, transmission, and reflectance of microwave and radar energycan be modified by coating or incorporating particles of metals or metaldielectric sandwiches. Superconducting materials such as magnesiumboride also can be made into angstrom scale particles.

Biological

By placing an anti fungal or antibacterial coating on these thinplatelets then incorporating them into inks and coating active agentscan be effectively transported to the surfaces.

Nanoparticles

Nanoparticles can be produced by vapor depositing a flake material asdiscrete particles. In the industry it is well known that nucleation andfilm growth play an important role in formation of quality PVD coatings.During the initial deposition nuclei are formed that grow in size andnumber as the deposition continues. As the process continues theseislands begin to join together in channels that later fill in to formthe final continuous film. To make nanoparticles, the coating processonly reaches the island stage before the next layer of releasingmaterial is applied. This allows the small particles to be trappedbetween the releasing layers in the multilayer construction describedbelow. They can later be released by dissolving the releasing materialwith the proper solvent.

Another process for making nanoscale particles is to produce the flakematerial below 50 angstroms and then reduce the particle diameter with asecondary operation.

Use of Flake Material in Coatings

Flake material was put into a coating for use in the above applicationsusing the following procedure:

Various material compositions of materials were converted into flakeform. The converted flake was then incorporated, on a surface areabasis, into a vehicle.

Vehicle Composition:

Toluene 28 pts Isopropanol 28 pts Methyl Ethyl Ketone 28 pts Elvacite2042 16 pts

The actual weight of the flake used in this example was derived by thethickness and the density of the chemical compound. This derivation wasused to study the effect of the chemical compound. The flake wassupplied in a slurry form in acetone. The first step in the process wasto measure the percent solids by weight. After finding the solids, theamount of slurry material to use can be determined by the followingtable.

Thickness Dry flake Weight to of the per 100 g Percent wt use per 100 gMaterial Density flake vehicle solution solids of slurry vehicle sol.Titanium 4.26 200 A 0.09 g Dioxide Titanium 4.93 200 A 0.08 g MonoxideSilicon Dioxide 2.2 200 A 0.20 g Silcone 2.13 200 A 0.20 g MonoxideAluminum 3.97 200 A 0.10 g Oxide Indium Oxide 7.13 200 A 0.06 g IndiumTin 4.48 200 A 0.09 g Oxide Zinc Oxide 5.6  75 A 0.03 g Indium 7.3 200 A0.06 g Magnesium 3.18 200 A 0.13 g Fluoride Silicone 2.33 200 A 0.016 g The flake was mixed into the vehicle at the appropriate weight. Theslurry was then coated onto a gloss polyester film, 0.002 inches thick,to achieve a final coating thickness of 2.6 to 3.0 g/m². The coating wasallowed to dry then tested in two ways.

Method for Evaluating Heat Reflective Properties:

The prepared coatings were transferred to the surface of a sheet ofrigid polyvinyl chloride (PVC) decorated with EF18936L using heat andpressure. The polyester film was removed after transfer. Three inch bythree inch panels were prepared with a blank (vehicle without flake) andthe test flake. These panels were then evaluated using the ASTMD4809-method for predicting heat buildup in PVC building products. Theresults were reported for both the blank and the test flake panel.

Method of Evaluating UV Screening Properties:

A base test sheet was prepared by applying a film comprising of thefollowing materials to a rigid PVC sheet:

Color Coat I80126 Vehicle 59.5 pts I80161 White Dispersion 27.0 ptsI8980 Isoindolinone Yel Disp  5.4 pts MEK Methyl Ethyl Ketone  8.1 pts

Apply to 0.002 mil gloss polyester using 2-137HK printing plates

-   -   Size L56537

Apply after color coats using 1-137HK printing plate

The blank and slurry are prepared on polyester as in the previous methodand transferred to the panels described above. Both the blank and thetest flake panel are placed in a Sunshine Carbon Arc (Atlas)weatherometer set up on the Dew Cycle protocol. Initial gloss and colorreadings are taken and recorded every 500 hours of operating time.

The multilayer particle releasing layer can be made from conventionalorganic solvent-based polymers deposited in a PVD process. A number ofdifferent materials can be used such as polymers, oligimers, andmonomers. These materials can be evaporated by electron beam,sputtering, induction, and resistance heating.

One of the difficulties with using bulk polymer in this process is toeffectively feed the polymer into the evaporating system without itsbeing exposed for long periods of time to high temperature, which canhave detrimental effects. Another difficulty is evaporating andconducting the polymer vapor to the support system while notcontaminating the vacuum system or degrading the vacuum.

Several approaches can overcome these problems with polymer delivery.One approach is to coat the polymer onto a carrier material such as awire or ribbon made of metal or material that can withstand thetemperatures of vaporization. This coated material is then fed into thepolymer vapor die where it is heated and the polymer is vaporized andthe vapor is conducted to the support system. Another approach is tomelt the polymer and reduce its viscosity and then extrude or pump thematerial into the polymer vapor die. A gear pump, extruder, or capillaryextrusion system (Capillary Rehometer) like the polymer vapor die canprovide a vaporizing surface that is heated to the appropriatetemperature. The die then conducts the vapor to the support system. Itis necessary to provide a cooled surface to condense any stray polymervapor that leaves the polymer die support system area and differentiallypump this area as well.

Bell Jar Process

Referring to FIG. 10, a vacuumizable bell jar 100 is modified with aheater block 102 installed on the floor of the bell jar. The blockcomprises a heated polymer vapor chamber 104 having a cavity 106 carvedout to hold the desired sample. A crucible 108 made of aluminum foil isfitted to the block and approximately 0.3 g of the desired material isplaced in the crucible. The crucible is then placed in the heater block.

Above the heater block, a deposition gauge 109 is positioned one inchfrom the top of the block. As the block is heated, this gauge willmeasure the amount of material evaporated in angstroms per second(Å/sec).

Above the deposition gauge, a polyester sheet 110 is clamped between twoposts (not shown). The material evaporated from the block is depositedon this film. In another step, this film is metallized.

Once the sample, deposition gauge, and polyester film are in place, thebell jar is closed and the vacuum cycle is started. The system isevacuated to a pressure between 2×10⁻⁵ torr and 6×10⁻⁵ torr and thetrial is ready to begin.

The heater block begins at approximately room temperature. Once thedesired vacuum is achieved, power to the block is turned on. The blockis set to ramp up to 650° C. in a 20 minute interval. Measurements aretaken every minute. The time, current block temperature (° C.),deposition gauge reading (Å/sec), and current vacuum pressure (torr) aredocumented each minute. The trial ends when either the deposition gaugecrystal fails or when all of the material has been evaporated and thedeposition gauge reading falls to zero.

At the end of the trial, the bell jar is opened to atmosphere. Thepolyester is removed and set aside to be metallized and the spentcrucible is discarded. The data is then charted for comparison to allother materials run.

Bell Jar Polymer Trials

Several experiments were run on different polymers in the bell jarmetallizer. The procedure described in “Bell Jar Procedure” was followedfor all of these experiments. For each experiment, the trial time,temperature, deposition gauge reading, and vacuum pressure weredocumented. From these data it can be determined what materials havegreater effect on the vacuum and which material provide the highestdeposition rates. A higher deposition rate means an eventualmanufacturing sized apparatus will be able to run at higher speeds.However, materials that have greater effects on the vacuum pressurecould cause cleanup and possible pump down problems after extendedperiods of operation.

Trials 1, 2, 6, and 7 were run using the Dow 685D polystyrene. Thispolymer has a reported molecular weight of about 300,000. All fourtrials produced similar results. Deposition rates held at around 10Å/sec until a temperature of approximately 550° C. was reached. Up untilthat temperature, there was very little effect on the vacuum. Thepressure was generally raised less than 2×10⁻⁵ torr. Above 550° C. therate rose dramatically and the pressure rose into the range of 1.2×10⁻¹to 1.8×10⁻¹ torr. This is still a minimal impact on the vacuum pressure.

Trial 3 was run with Elvacite 2045, an isobutyl methacrylate with amolecular weight of 193,000. The deposition rose as high as 26.5 Å/secat a temperature of 500° C. At this temperature the vacuum pressure hadrisen to 3.6×10⁻⁴ torr from a starting pressure of 5.2×10⁻⁵ torr.

The fourth trial used Elvacite 2044, which is an n-butyl methacrylatematerial with a molecular weight of 142,000.

Deposition for the 2044 reached a peak of 30 Å/sec at 500° C. At thistemperature the vapor pressure reached 2.0×10⁻⁴ torr.

Trials 5 and 19 were run with Endex 160, which is a copolymer material.The Endex 160 reached its maximum deposition at 413° C. with a rate of11 Å/sec. The deposition had almost no impact on the vacuum as it wasultimately only raised by 1.0×10⁻⁶ torr to a final reading of 4.4×10⁵torr.

The eighth trial was run with Elvacite 2008, a methyl methacrylatematerial with a molecular weight of 37,000. The highest deposition ratewas achieved at 630° C. with a rate of 67 Å/sec. The final vacuumpressure was raised to 1.0×10⁻⁴ torr.

and 10 were run with Piccolastic D125. This material is a styrenepolymer with a molecular weight of 50,400. Deposition rates of 108 Å/secwere reached at 500° C. and throughout the trials there was minimalimpact on the vacuum.

and 12 were run with Piccolastic A75. This is another styrene monomer,but with a low molecular weight of 1,350. Deposition rates started veryearly and rose to a maximum of 760 Å/sec when the temperature reached420° C. For both trials there was once again very minimal impact on thevacuum pressure.

Trials 13 and 14 were run with a 50,000 MW polystyrene standard fromPolyscierice. These samples have very tight molecular weightdistributions. For these trials, a deposition of 205 Å/sec was achievedat a temperature of 560° C. At that deposition, the vacuum pressure roseto 6.2×10⁻⁵ torr, a rise of 1.4×10⁻⁵ torr over the starting pressure.

and 16 were run with another polystyrene standard from Polyscience, butthis one had a molecular weight of 75,000. Deposition reached a rate ofabout 30 Å/sec at a temperature of 590° C. At this temperature, thevacuum pressure had risen to 3.0×10⁻⁴ torr, a fairly significant rise.

Trial 17 was run with Endex 155, a copolymer of aromatic monomers with amolecular weight of 8,600. The maximum deposition was reached at 530° C.with a rate of 78 Å/sec. At the end of the trial the vacuum pressure hadrisen to 1.0×10⁻⁴ torr.

Trial 18 was another polystyrene standard from Polyscience. This samplehad a molecular weight range of 800-5,000. Deposition was as high as 480Å/sec at a temperature of 490° C. There was little to no impact on thevacuum pressure during the entire run.

Trial 20 was run with a standard of polymethyl methacrylate fromPolyscience. This sample had a molecular weight of 25,000. A finaldeposition rate was achieved at 645° C. with a rate of 50 Å/sec. At thiscondition, the vacuum pressure had risen to 1.0×10⁴⁴ torr.

Trial 21 was run with Elvacite 2009, a methyl methacrylate polymertreated to contain no sulfur. The molecular weight of this material was83,000. A final deposition rate of 26 Å/sec was reached at a temperatureof 580° C. The vacuum pressure had risen to 1.8×10⁻⁴ torr from aninitial reading of 4.2×10⁻⁵ torr.

Trials 22 and 26 were run with Elvacite 2697, a treated version of amethyl/n-butyl methacrylate copolymer. The molecular weight of thismaterial was 60,000. The Elvacite 2697 had a final deposition rate of 20Å/sec at a temperature of 580° C. Vacuum pressure rose to 1.0×10⁻⁴ torrat the end of the trial.

Trial 23 was run with Elvacite 2021C, a treated methyl methacrylate.This material had a molecular weight of 119,000. A final deposition rateof 30 Å/sec was reached at 590° C. This trial had a significant impacton the vacuum as the final pressure was 4.4×10⁻⁴ torr, an order ofmagnitude increase over the initial vacuum pressure.

Trial 24 was run with Lawter K1717, a polyketone. A maximum depositionrate of 300 Å/sec was reached at 300° C. At this temperature the vacuumpressure had risen to 7.0×10⁻⁵ torr. At the end of the trial, a greatdeal of soot remained in the crucible. This indicated that some of thematerial had actually combusted rather than just being evaporated.

Trial 25 was run with Solsperse 24000, a dispersing agent. This samplealso left a soot residue in the crucible indicating combustion duringthe trial. However, there was a deposition rate recorded up to 100 Å/secat 360° C. The vacuum pressure rose 1.0×10⁻⁵ torr over the course of theexperiment.

Trial 27 was run with Elvacite 2016, a non-treated methyl/n-butylmethacrylate copolymer. This has a molecular weight of 61,000. At 630°C., the deposition rate reached 135 Å/sec. At this condition, the vacuumpressure had been significantly raised to 3.0×10⁻⁴¹ torr.

Trial 28 was run with Elvacite 2043, an ethyl methacrylate polymer witha molecular weight of 50,000. At 600° C., the deposition rate was at 98Å/sec. At this condition, the vacuum pressure was at 1.0×10⁻⁴ torr.

Trial 29 was run with Kraton G1780. This material is a multiarmcopolymer of 7% styrene and ethylene/propylene. Deposition reached ahigh of 70 Å/sec at a temperature of 600° C. The final vacuum pressurerose to 8.2×10⁻⁵ torr. During the trial, the deposition rate held verysteady and did not exhibit wild fluctuation that is common in all of theother trials, especially at higher temperatures.

Trial 30 was run with Kraton G1701. This material is a linear diblockpolymer of 37% styrene and ethylene/propylene. An ultimate depositionrate of 102 Å/sec was reached at a temperature of 595° C. The vacuumpressure was at 8.6×10⁻⁵ torr at this final condition.

Trial 31 was run with Kraton G1702. This is a linear diblock polymer of28% styrene and ethylene/propylene. A final deposition rate of 91 Å/secwas reached at 580° C. The vacuum pressure had risen to 8.0×10⁻⁵ torr atthis condition.

Trial 32 was run with Kraton G1730M. This is a linear diblock polymer of22% styrene and ethylene/propylene. The maximum deposition rate of 80Å/sec was reached at 613° C. At this temperature, the vacuum pressurewas 8.0×10⁻⁵ torr.

Trial 33 was run with 1201 Creanova, a synthetic resin based on aurethane modified ketone aldehyde. This material achieved a depositionrate of 382 Å/sec at a temperature of 535° C. At this temperature therewas minimal impact on the vacuum.

Trial 34 was run with Kraton G1750M. This is a multiarm copolymer of 8%styrene and ethylene/propylene. A deposition rate of 170 Å/sec wasreached at 625° C. At this condition, the vacuum pressure rose to 9×10⁻⁵torr.

From these trials we reached the following conclusions. The greatestvalue of these experiments came from quantifying the effect variousresins have on vacuum pressure. From the trials there appeared to be acorrelation with molecular weight to the vacuum impact. The lower themolecular weight of the material, the less impact the evaporatedmaterial will have on the vacuum pressure of the system. There does notappear to be a correlation between temperature and deposition.

Drum with Block Procedure

Referring to FIGS. 11 and 12, a vacuumizable chamber 112 contains arotating drum 114, a deposition gauge 116, and a heater block 118. Theheater block comprises a heated polymer vapor chamber 120 fitted with acrucible 122 having a polymer source 124. The drum 114 is approximatelyone foot in diameter and six inches wide on the surface. It can rotateat a maximum speed of two rotations per minute. The heater block iscylindrical in shape with a slot 126 carved into one area. The slot isopen into a cavity 128 running through the center of the block. Theblock has three independent heaters that can be used to control thetemperature of the block. The deposition gauge 116 is placedapproximately one inch in front of the slot. It can measure the amountof material passing through the slot in angstroms per second (Å/sec).This embodiment depicts an electron beam gun 130 in the vacuum chamber,but for this procedure, the EB gun is not used. This procedure can beused to screen polymers to determine their capability of being vapordeposited and therefore usable as a polymeric release coat.

To prepare a sample, the heater block can be opened and material isloaded into the cavity. Once this is done, the chamber is closed and thevacuum cycle is started. The chamber is evacuated until the pressuregets to at least 6×10⁻⁵ torr.

The block begins at around room temperature. Once the desired vacuum isachieved, power to the three heaters is turned on. The heaters are setto ramp up to the desired temperature in a 20-minute interval.Measurements are transmitted to a computer file approximately every sixseconds. The time, block temperature in three zones (° C.), depositiongauge reading (Å/sec), and current vacuum pressure (torr) aredocumented. The trial ends when either the deposition gauge crystalfails or when all of the material has been evaporated and the depositiongauge reading falls to zero.

At the end of the trial, the chamber is opened to atmosphere. Thedeposition crystal is changed and the block is loaded with new materialfor the next trial.

Polystyrene Trials in Polymer Block

Six separate trials were run using the Dow 685D polystyrene in eachtrial. This polystyrene is reported to have a molecular weight ofapproximately 300,000. In the trials, the ultimate block temperature wasvaried as well as the ramp time to reach the final temperature.

In trial 1, the block was programmed to reach 300° C. in a ramp time of10 minutes. As the trial progressed, the polymer deposition rate wasvery low at no higher than 5 Å/sec. This rate held during the entiretrial.

In the second trial the block was programmed to reach a finaltemperature of 325° C. with no ramp time set. The controllers wereallowed to increase the temperature at their maximum possible rate. Astemperature was reached, the deposition rate leveled out at about 30Å/sec. With some fluctuation, this rate held constant until 15 minutesinto the trial when the rate began to noticeably drop. By the end of thetrial at 20 minutes, the rate had fallen to 15 Å/sec. This rate decreaseis likely due to the exhaustion of the polymer supply.

In the third trial the block was set to reach an ultimate temperature of350° C. in a ramp time of 10 minutes. As the temperature was reached,the deposition rate was at about 6 Å/sec. As the trial progressed therate finally reached a peak of 14 Å/sec about 13 minutes into theexperiment. By the end of the trial at 20 minutes the rate had fallenback to about 6 Å/sec. Polystyrene is theorized to begin adepolymerization at about 350° C. The deposition rate in the experimentmay have been lower because the temperature was causing thisdepolymerization as well as the evaporation that would be sensed up bythe deposition gauge.

Trial 4 had a 375° C. setpoint with no ramp to temperature. Thedeposition rate rose to 30-35 Å/sec in about 10 minutes, but did nothold steady there. As the temperature passed 350° C., the rate rosesignificantly and became erratic. The rate fluctuated from 40-120 Å/secwith no regular pattern. After 15 minutes of trial time, the depositiongauge crystal failed and the experiment was stopped. Above 350° C. thepolymer has absorbed enough energy to depolymerize, so from that pointon it liberates very low molecular weight material at high rates. Thismaterial includes monomers and dimers of the original polystyrene. Thislow end material is not useful in forming a polymer film.

The fifth trial also had a 375° C. final temperature, but this time witha 10 minute ramp time. The deposition was very steady at first, but onceagain above 350° C. the deposition became erratic. The rate fluctuatedfrom 20 Å/sec to a peak of 110 Å/sec. The trial ended at about 18minutes when the gauge crystal failed.

The final trial was at a 375° C. temperature, but with a 20 minute ramptime. The same behavior was exhibited as the previous two trials. Up toa temperature of 350° C. the deposition was fairly steady at a rate ofabout 20 Å/sec. As the temperature rose through 350° C. though, the rateonce again became erratic. The rate fluctuated between 30 and 140 Å/secand crystal failure once again caused the end of the experiment, thistime at 23 minutes.

From these trials we reached the following conclusions. It appears thatpolystyrene exhibiting depolymerization or other physical breakdown at atemperature of approximately 350° C. is shown to be true in theseexperiments. In the trials above that temperature, the erratic behavioroccurred at approximately the same temperature in all three cases. Inthe trial at 350° C., the deposition rate indicated another process wastaking place since a higher rate was seen at the lower 325° C. setpoint.Unless a depolymerization or other process was taking place, thedeposition rate at 350° C. should have been higher than the rate at 325°C. Also, for the trials at 375° C., an oily film was observed at the endof the trial. This material was shown to be polystyrene under FTIRanalysis and the oily nature indicates it is likely a low molecularweight species of the polystyrene. This is further evidence that theoriginal polymer (300,000 MW) was depolymerized. The trial at 350° C.left a slightly tacky residue, but it was not as oily as the residuefrom the 375° C. trials. The experiments run at 300° C. and 325° C. hada solid film left behind with no indication of tackiness or oil. Fromthis set of experiments, it appears that a range of more than about 300°C. to less than about 350° C., and more preferably 325° C. is atemperature at which to run polymer deposition. The preferredtemperature is low enough that polymer breakdown does not develop. Italso provides a fairly high deposition rate that holds steady throughoutthe run.

Drum with Block and E-Beam In Block Crucibles

The vacuum chamber 112, heater block 118 and rotating drum 114illustrated in FIGS. 11 and 12 are used in this embodiment, along withthe electron beam gun 130.

To add material, the heater block can be opened and material is loadedinto the cavity 128. The drum is covered with PET film. The E-beam gunis typical of those used in the industry. It has four copper hearths ona rotating plate. One hearth at a time is positioned in line with theE-beam gun. The material to be evaporated is placed directly in thehearth or in an appropriate crucible liner that is placed in the hearthat the proper turret location. A second deposition gauge (not shown) islocated near the drum surface, above the crucible. It can measure theamount of material evaporated from the crucible in angstroms per second(Å/sec). Once this is done, the chamber is closed and the vacuum cycleis started. The chamber is evacuated until the pressure gets to at least6×10⁻⁵ torr.

Once the desired vacuum is achieved, power to the three heaters isturned on. The heaters are set to ramp up to the desired temperature ina 20-minute interval. Measurements are transmitted to a computer fileapproximately every six seconds. The time, block temperature in threezones (° C.), deposition gauge readings (Å/sec), and current vacuumpressure (torr) are documented. Power is supplied to the E-beamapparatus. It is possible to raise the power to the gun in increments of0.1%. The power is raised to a point just below evaporation and allowedto soak or condition. After soaking, the power is raised until thedesired deposition rate is achieved then a shutter is opened once thepolymer begins to deposit. The rotation of the drum is started. Thetrial ends if either the deposition gauge crystal fails or when all ofthe material has been evaporated and the deposition gauge reading fallsto zero. At the end of the trial, the E-beam shutter is closed, the drumrotation is stopped, the power is disconnected from the E-beam, and theblock heater is turned off. After a cool down period, the chamber isopened to atmosphere. The coated material is removed.

Flake Materials Run in E-Beam

The following materials were deposited in the E-beam metallizer and weremade into flake materials. They were microphotographed as describedbelow.

DEPOSITION RATE THICKNESS TARGET METAL (Angstroms/sec) POWER (Angstroms)COMMENTS Indium Metal 80 10.6% 475 Silvery Appearance Magnesium 80 7.9%475 Very clear film Fluoride Silicon Monoxide 80 8.6% 475 Brown,Transparent Film Titanium Dioxide 25 10.4% ~400 Clear, Iridescent FilmZinc Oxide 30 10.9% ~200 Black residue everywhere Aluminum Oxide 6010.8% 350 Clear, slight iridescence Indium Oxide 60 10.1% 350 SilveryFilm Indium Tin Oxide 60 10.3% 350 Silvery Film Chromium Metal 60 14%350 Chrome colored Sandwich of SiO/Al/SiO Silicon Metal 60 12.2% 350Silvery Film Phelly Materials 60 9.8% 350 Copper colored film CopperAlloy Copper (only enough to get a vial of flake) Copper colored flakeExamples from the above table:

Appendix Example 1

The following construction was made: A roll of 48 gauge polyesterprinted with a thermoplastic release coat was metallized in a Temiscalelectron beam metallizer with indium. The roll was removed from themetallizer and run through a laboratory stripper using acetone toseparate the indium from the polyester. The indium and acetone solutionwas then decanted and centrifuged to concentrate the flakes. Theresulting flakes were than drawn down on a slide and microphotographedon an Image Pro Plus Image Analyzer from Media Cybernetics. The flakesin solution were then reduced in particle size using an IKA Ultra TurexT50 Homogenizer. A particle size distribution was taken on the resultingflake using a Horiba LA 910 laser scattering particle size distributionanalyzer. The particle sizes reported below are according to thefollowing conventions: D10: 10% of the particles measured are less thanor equal to the reported diameter; D50: 50% of the particles measuredare less than or equal to the reported diameter; D90: 90% of theparticles measured are less than or equal to the reported diameter. Thefinished particle size of the flake was D10=3.3, D50=13.2, D90=31.2.

The photograph at page 1 of the Appendix illustrates:

Indium homogenized 30″

Particle size homogenized 30″ in microns:

D10=8.21, D50=26.68, D90=65.18

Homogenized 6 minutes 30 seconds.

Finish particle size in microns:

D10=3.33, D50=13.21, D90=31.32

Appendix Example 2

The following construction was made: A roll of 48 gauge polyesterprinted with a thermoplastic release coat was metallized in the Temiscalelectron beam metallizer with Ti0₂. The roll was removed from themetallizer and run through a laboratory stripper using acetone toseparate the Ti0₂ from the polyester. The TiO₂ and acetone solution wasthen decanted and centrifuged to concentrate the flakes. The resultingflakes were than drawn down on a slide and microphotographed on an ImagePro Plus Image Analyzer from Media Cybernetics. The flakes in solutionwere then reduced in particle size using an IKA Ultra Turex T50Homogenizer. A particle size distribution was taken on the resultingflake before and after homogenization using a Horiba LA 910 laserscattering particle size distribution analyzer.

The photograph at page 2 of the Appendix illustrates:

TiO₂ “as is” before particle sizing.

Particle size in microns:

D10=16.20, D50=44.17, D90=104.64

Homogenized 15 minutes.

Finish particle size in microns:

D10=7.83, D50=16.37, D90=28.41

Appendix Examples 3 and 4

The following construction was made: A roll of 48 gauge polyesterprinted with a thermoplastic release coat was metallized in the Temiscalelectron beam metallizer with MgF₂. The roll was removed from themetallizer and run through a laboratory stripper using acetone toseparate the MgF₂ from the polyester. The MgF₂ and acetone solution wasthen decanted and centrifuged to concentrate the flakes. The resultingflakes were than drawn down on a slide and microphotographed on an ImagePro Plus Image Analyzer from Media Cybernetics. The flakes in solutionwere then reduced in particle size using an IKA Ultra Turex T50Homogenizer. A particle size distribution was taken on the resultingflake before and after homogenization using a Horiba LA 910 laserscattering particle size distribution analyzer.

The photographs at pages 3 and 4 of the Appendix illustrate:

MgF₂ pictured “as is” before particle sizing.

Particle size in microns:

D10=16.58, D50=150.34, D90=398.17

Homogenized 11 minutes.

Finished particle size in microns:

D10=0.43, D50=16.95, D90=45.92

Appendix Examples 5 and 6

The following construction was made: A roll of 48 gauge polyesterprinted with a thermoplastic release coat was metallized in the Temiscalelectron beam metallizer with SiO. The roll was removed from themetallizer and run through a laboratory stripper using acetone toseparate the SiO from the polyester. The SiO and acetone solution wasthen decanted and centrifuged to concentrate the flakes. The resultingflakes were than drawn down on a slide and microphotographed on an ImagePro Plus Image Analyzer from Media Cybernetics. The flakes in solutionwere then reduced in particle size using an IKA Ultra Turex T50Homogenizer. A particle size distribution was taken on the resultingflake before and after homogenization using a Horiba LA 910 laserscattering particle size distribution analyzer.

The photographs at pages 5 and 6 of the Appendix illustrate:

SiO pictured “as is” before particle sizing.

Particle Size in microns:

D10=17.081, D50=67.80, D90=188.31

Homogenized 17 minutes.

Finished particle size in microns:

D10=5.75, D50=20.36, D90=55.82

Appendix Examples 7, 8 and 9

The following construction was made: A roll of 48 gauge polyesterprinted with a thermoplastic release coat was metallized in the Temiscalelectron beam metallizer with ZnO. The roll was removed from themetallizer and run through a laboratory stripper using acetone toseparate the ZnO from the polyester. The ZnO and acetone solution wasthen decanted and centrifuged to concentrate the flakes. The resultingflakes were than drawn down on a slide and microphotographed on an ImagePro Plus Image Analyzer from Media Cybernetics. The flakes in solutionwere then reduced in particle size using an IKA Ultra Turex T50Homogenizer. A particle size distribution was taken on the resultingflake before and after homogenization using a Horiba LA 910 laserscattering particle size distribution analyzer.

The photographs at pages 7, 8 and 9 of the Appendix illustrate:

ZnO pictured “as is” before particle sizing.

Particle size in microns:

D10=23.58, D50=63.32, D90=141.59

Finished particle size in microns:

D10=7.69, D50=18.96, D90=38.97

Appendix Examples 10, 11 and 12

The following construction was made: A roll of 48 gauge polyesterprinted with a thermoplastic release coat was metallized in the Temiscalelectron beam metallizer with Al₂O₃. The roll was removed from themetallizer and run through a laboratory stripper using acetone toseparate the Al₂O₃ from the polyester. The Al₂O₃ and acetone solutionwas then decanted and centrifuged to concentrate the flakes. Theresulting flakes were than drawn down on a slide and microphotographedon an Image Pro Plus Image Analyzer from Media Cybernetics. The flakesin solution were then reduced in particle size using an IKA Ultra TurexT50 Homogenizer. A particle size distribution was taken on the resultingflake before and after homogenization using a Horiba LA 910 laserscattering particle size distribution analyzer.

The photographs at pages 13 and 14 of the Appendix illustrate:

Al₂O₃ pictured “as is” before particle sizing.

Particle Size in microns:

D10=6.37, D50=38.75, D90=99.94

Homogenized 9 minutes.

Finished particle size in microns:

D10=1.98, D50=16.31, D90=39.77)

Appendix Examples 13 and 14

The following construction was made: A roll of 48 gauge polyesterprinted with a thermoplastic release coat was metallized in the Temiscalelectron beam metallizer with In₂O₃. The roll was removed from themetallizer and run through a laboratory stripper using acetone toseparate the In₂O₃ from the polyester. The In₂O₃ and acetone solutionwas then decanted and centrifuged to concentrate the flakes. Theresulting flakes were than drawn down on a slide and microphotographedon an Image Pro Plus Image Analyzer from Media Cybernetics. The flakesin solution were then reduced in particle size using an IKA Ultra TurexT50 Homogenizer. A particle size distribution was taken on the resultingflake before and after homogenization using a Horiba LA 910 laserscattering particle size distribution analyzer.

The photographs at pages 13 and 14 of the Appendix illustrate:

In₂O₃ Pictured “as is” before particle sizing.

Particle size in microns:

D10=18.88, D50=50.00, D90=98.39

Homogenized 3 minutes.

Finished particle size in microns:

D10=8.89, D50=20.22, D90=38.92

Relative Refractive Index used: 2.64-2.88

Appendix Examples 15, 16 and 17

The following construction was made: A roll of 48 gauge polyesterprinted with a thermoplastic release coat was metallized in the Temiscalelectron beam metallizer with indium tin oxide (ITO). The roll wasremoved from the metallizer and run through a laboratory stripper usingacetone to separate the ITO from the polyester. The ITO and acetonesolution was then decanted and centrifuged to concentrate the flakes.The resulting flakes were then drawn down on a slide andmicrophotographed on an Image Pro Plus Image Analyzer from MediaCybernetics. The flakes in solution were than reduced in particle sizeusing an IKA Ultra Turex T50 Homogenizer. A particle size distributionwas taken on the resulting flake before and after homogenization using aHoriba LA 910 laser scattering particle size distribution analyzer.

The photographs at pages 15, 16, and 17 of the Appendix illustrate:

ITO pictured “as is” before particle sizing.

Particle size in microns:

D10=21.70, D50=57.00, D90=106.20

Homogenized 6 minutes.

Finished particle size in microns:

D10=10.40, D50=20.69, D90=36.32

Appendix Examples 18, 19, 20 and 21

The following construction was made: A roll of 48 gauge polyesterprinted with a thermoplastic release coat was metallized in the Temiscalelectron beam metallizer with Si. The roll was removed from themetallizer and run through a laboratory stripper using acetone toseparate the Si from the polyester. The Si and acetone solution was thendecanted and centrifuged to concentrate the flakes. The resulting flakeswere then drawn down on a slide and microphotographed on an Image ProPlus Image Analyzer from Media Cybernetics. The flakes in solution werethan reduced in particle size using an IKA Ultra Turex T50 Homogenizer.A particle size distribution was taken on the resulting flake before andafter homogenization using a Horiba LA 910 laser scattering particlesize distribution analyzer.

The photographs at Appendix pages 18, 19, 20 and 21 illustrate:

Si pictured “as is” before particle sizing.

Particle size in microns:

D10=20.20, D50=57.37, D90=140.61

Homogenized 20 minutes.

Finished particle size in microns:

D10=11.9, D50=27.0, D90=55.5

Appendix Examples 22 and 23

The following construction was made: A roll of 48 gauge polyesterprinted with a thermoplastic release coat was metallized in the Temiscalelectron beam metallizer with a sandwich of SiO, Al, SiO. The roll wasremoved from the metallizer and run through a laboratory stripperusingacetone to separate the sandwiches from the polyester. The SiO, Al,SiO and acetone solution was then decanted and centrifuged toconcentrate the flakes. The resulting flakes were then drawn down on aslide and microphotographed on an Image Pro Plus Image Analyzer fromMedia Cybernetics. The flakes in solution were than reduced in particlesize using an IKA Ultra Turex T50 Homogenizer. A particle sizedistribution was taken on the resulting flake before and afterhomogenization using a Horiba LA 910 laser scattering particle sizedistribution analyzer.

The photographs at Appendix pages 22 and 23 illustrates:

SiO Al SiO sandwich pictured “as is” before particle sizing

Particle size in microns:

D10=29.7, D50=77.6, D90=270.2

Appendix Examples 24 and 25

The following construction was made: A roll of 48 gauge polyesterprinted with a thermoplastic release coat was metallized in the Temiscalelectron beam metallizer with chromium. The roll was removed from themetallizer and run through a laboratory stripper using acetone toseparate the chromium from the polyester. The chromium and acetonesolution was then decanted and centrifuged to concentrate the flakes.The resulting flakes were then drawn down on a slide andmicrophotographed on an Image Pro Plus Image Analyzer from MediaCybernetics. The flakes in solution were than reduced in particle sizeusing an IKA Ultra Turex T50 Homogenizer. A particle size distributionwas taken on the resulting flake before and after homogenization using aHoriba LA 910 laser scattering particle size distribution analyzer.

The photographs at Appendix 24 and 25 illustrate:

Chromium pictured “as is” before particle sizing

Particle size in microns:

D10=13.1, D50=8.9, D90=59.8

Homogenized 3 minutes

Finished particle size in microns:

D10=9.82, D50=19.81; D90=37.55

Appendix Example 26

The following construction was made: A roll of 48 gauge polyesterprinted with a thermoplastic release coat was metallized in the Temiscalelectron beam metallizer with an M-401 copper, zinc, silver alloy, PhenyMaterials, Emerson, N.J. The roll was removed from the metallizer andrun through a laboratory stripper using acetone to separate the alloyfrom the polyester. The alloy and acetone solution was then decanted andcentrifuged to concentrate the flakes. The resulting flakes were thendrawn down on a slide and microphotographed on an Image Pro Plus ImageAnalyzer from Media Cybernetics. The flakes in solution were thanreduced in particle size using an IKA Ultra Turex T50 Homogenizer. Aparticle size distribution was taken on the resulting flake before andafter homogenization using a Horiba LA 910 laser scattering particlesize distribution analyzer.

The photograph at Appendix page 26 illustrates:

Alloy pictured “as is” before particle sizing

Particle size in microns:

D10=69.6, D50=161.2, D90=313.4

Homogenized 20 minutes

Finished particle size in microns:

D10=13.32, D50=27.77, D90=51.28

FIGS. 13 and 14 show a vacuum chamber, rotating drum and polymer vaporchamber similar to FIGS. 11 and 12, except that the polymer is deliveredto the chamber by a wire feed mechanism 136 described in more detailbelow. In this embodiment, the heater block has small holes in both endsthat allow a coated wire 143 to pass into the heated slot area. Thecoated wire is unwound from a spool 164 and advanced at a predeterminedrate through the block where the polymer is evaporated into the slotarea then the spent wire is rewound on a second spool 166. The slot isopen into a cavity running through the center of the block. In thisembodiment, the area around the heater block and drum is pumped toselectively cool that area for condensing the polymers coated on thewire. This prevents escape of vapor toward the E-beam area of thechamber.

Appendix Example 27 Example Drum with Polymer Block and E-Beam (WireFeed)

Release Styron Support Aluminum Material Material Supplier Dow SupplierMat. Research Corp No. 685D No. 90101E-AL000-30002 PVD Conditions:Release E-Beam Thickness Support Drum Wire Coat Wire Power (Angstroms)Thickness Speed Revolutions Size Weight Speed 15% 200 150 1 RPM 1000.005 in./ 0.0005 gms/in 6 Angstroms diaThe following construction was made at the conditions shown above: 48gauge polyester wrapped around the drum for easy removal was polymerrelease coated with styrene and metallized in the Temiscal electron beammetallizer with aluminum. The polyester film was removed from themetallizer and run through a laboratory releasing device using acetoneto separate the aluminum from the releasing layers and the polyesterfilm. The aluminum and acetone solution was then decanted andcentrifuged to concentrate the flakes. The resulting flakes were thandrawn down on a slide and microphotographed on an Image Pro Plus ImageAnalyzer from Media Cybernetics. The flakes in solution were thenreduced in particle size using an IKA Ultra Turex T50 Homogenizer. Aparticle size distribution was taken on the resulting flake using aHoriba LA 910 laser scattering particle size distribution analyzer.

The photographs at page 27 of the Appendix illustrates:

Starting Particle size

D10=13.86, D50=34.65, D90=75.45.

Homogenized

Finished particle size in microns D105.10, D50=13.19, D90=25.80

Appendix Example 28 Example Drum with Polymer Block and E-Beam (WireFeed)

Release Styron Support Silicone Dioxide Material Material Supplier DowSupplier Cerac No. 685D No. S-1060 PVD Conditions: Release E-BeamThickness Support Drum Wire Coat Wire Power (Angstroms) Thickness SpeedRevolutions Size Weight Speed 8% 200 200 1 RPM 100 0.005 in./ 0.0005gms/in 6 Angstroms diaThe following construction was made at the conditions shown above: 48gauge polyester wrapped around the drum for easy removal was polymerrelease coated with styrene and metallized in the Temiscal electron beammetallizer with silicone monoxide. The polyester film was removed fromthe metallizer and run through a laboratory releasing device usingacetone to separate the silicon monoxide from the releasing layers andthe polyester film. The silicon monoxide and acetone solution was thendecanted and centrifuged to concentrate the flakes. The resulting flakeswere then drawn down on a slide and microphotographed on an Image ProPlus Image Analyzer from Media Cybernetics.

The flakes are shown in the photograph in Appendix page 28.

Appendix Example 29 Example Drum with Polymer Block and E-Beam (WireFeed)

Release Styron Support Magnesium Fluoride Material Material Supplier DowSupplier Cerac No. 685D No. M-2010 PVD Conditions: Release E-BeamThickness Support Drum Wire Coat Wire Power (Angstroms) Thickness SpeedRevolutions Size Weight Speed 7.5% 200 200 1 RPM 100 0.005 in./ 0.0005gms/in 6 Angstroms diaThe following construction was made at the conditions shown above: 48gauge polyester wrapped around the drum for easy removal was polymerrelease coated with styrene and metallized in the Temiscal electron beammetallizer with magnesium fluoride. The polyester film was removed fromthe metallizer and run through a laboratory releasing device usingacetone to separate the magnesium fluoride from the releasing layers andthe polyester film.

The magnesium fluoride and acetone solution was then decanted andcentrifuged to concentrate the flakes. The resulting flakes were thandrawn down on a slide and microphotographed on an Image Pro Plus ImageAnalyzer from Media Cybernetics.

The flakes are shown in the photograph at Appendix page 29.

Drum with Vapor Tube and E-beam Wire Feed

FIGS. 15, 16, 15A and 16A show two separate embodiments of a wire feedmechanism for delivering coated polymer to a vacuum chamber whichincludes a rotating drum, a deposition gauge, a polymer vapor tube witha coated polymer coated wire feed system, and an electron beam (E-beam)gun. The drum is as described previously. The vapor tube is equippedwith a heated polymer vapor path surrounded by a water-cooled tubeseparated by a vacuum gap. A slot in the tubes allows the evaporatedpolymer to pass through to the drum surface. The vapor tube produces adifferential pressure area adjacent the heater block and drum forpreventing escape of vapor to the E-beam area of the chamber. In theembodiment shown in FIGS. 15 and 16, the wire feed housing contains awire supply spool and a take-up spool. The wire is unwound and coatedwith polymer and runs around the heater block. Polymer is evaporatedfrom the coated wire and is directed onto the drum surface. The end viewof FIG. 16 shows the outer tube with its slot facing the drum. The outertube is cooled and the vapor tube inside is heated. This view also showsthe heater block with the wire wrap. The wire passes into the vaportube, around the heated tube and back out to the take-up spool.

The embodiment of FIGS. 15 and 16 shows a vacuum chamber 132 and heaterblock 134 similar to those previously described, except that polymer forthe release layers is fed into the vacuum chamber via the coated wirefeed apparatus 136. The vacuum chamber includes a rotating drum 128, adeposition gauge 140 and an electron beam (E-beam) gun 142. As mentionedpreviously, the drum is approximately one foot in diameter and sixinches wide on the surface. It can rotate at a maximum speed of tworotations per minute. The heater block 134 comprises a heated polymervapor chamber 144 which is cylindrical in shape with a slot 145 carvedinto one area. The heated inner tube is shown at 146. The wire feedapparatus 136 includes an elongated housing 147 containing a wire 148which is coated with polymer and then fed into the heater block. Thewire wraps around a heated shoe 149. The wire feed apparatus alsoincludes a turbo pump 150, an ion gauge and a thermocouple gauge 154.The coated wire is unwound from a spool 156 and advanced at apredetermined rate through the heater block where the polymer isevaporated into the slot area 158 and then the spent wire is rewound ona second spool 160. The slot is open into a cavity running through thecenter of the heater block. The pump assists in delivering vaporizedpolymer to the drum surface. The heater block has three independentheaters that can be used to control the temperature of the block. Thedeposition gauge 140 is placed approximately one inch in front of theslot. It can measure the amount of material passing through the slot inangstroms per second (Å/sec).

In use, the drum is covered with PET film. The wire feed mechanism andheater block are used to coat a layer of polymeric release material onthe carrier, followed by activating the E-beam gun to coat a layer ofmetal or other material on the release coat, and so on. The E-beam gun142 is typical of those used in the industry. It has four copper hearthson a rotating plate. One hearth at a time is positioned in line with theE-beam gun. The material to be evaporated is placed directly in thehearth or in an appropriate crucible liner that is placed in the hearthat the proper turret location. A second deposition gauge (not shown) islocated near the drum surface, above the crucible. It can measure theamount of material evaporated from the crucible in angstroms per second(Å/sec). Once this is done, the chamber is closed and the vacuum cycleis started. The chamber is evacuated until the pressure gets to at least6×10⁻⁵ torr.

Once the desired vacuum is achieved, power to the three heaters isturned on. The heaters are set to ramp up to the desired temperature ina 20-minute interval. Measurements are transmitted to a computer fileapproximately every six seconds. The time, block temperature in threezones (° C.), deposition gauge readings (Å/sec), and current vacuumpressure (torr) are documented. Power is supplied to the E-beamapparatus. It is possible to raise the power to the gun in increments of0.1%. The power is raised to a point just below evaporation and allowedto soak or condition. After soaking, the power is raised until thedesired deposition rate is achieved then a shutter is opened and thepolymer coated wire mechanism is set to the desired rate and depositionof polymer begins. The rotation of the drum is started. At the end ofthe trial, the E-beam shutter is closed, the drum rotation is stopped,the power is disconnected from the E-beam, the block heater and wirefeed is turned off. After a cool down period, the chamber is opened toatmosphere. The coated material is removed.

In the embodiment shown in FIGS. 15A and 16A, the vapor tube has smallholes in both ends that allow the coated wire 162 to pass into a heatedblock in the vapor tube. The coated wire is unwound from a first spool164 and advanced at a predetermined rate through the tube where thepolymer is evaporated into the slot area 158 and then the spent wire isrewound on a second spool 166. The vapor tube walls are heated by stripheaters and the block has an independent heater that can be used tocontrol the temperature of the system. A deposition gauge 168 is placedapproximately one inch in front of the slot. It can measure the amountof material passing through the slot in angstroms per second (Å/sec).

The drum is covered with PET film. The E-beam gun has four copperhearths on a rotating plate. One hearth at a time is positioned in linewith the E-beam gun. The material to be evaporated is placed directly inthe hearth or in an appropriate crucible liner that is placed in thehearth at the proper turret location. A second deposition gauge (notshown) is located near the drum surface, above the crucible. It canmeasure the amount of material evaporated from the crucible in angstromsper second (Å/sec). Once this is done, the chamber is closed and thevacuum cycle is started. The chamber is evacuated until the pressuregets to at least 6×10⁻⁵ torr. Once the desired vacuum is achieved, powerto the tube and block heaters is turned on. The heaters are set to rampup to the desired temperature in a 20-minute interval. Measurements aretransmitted to a computer file approximately every six seconds. Thetime, block temperature in three zones (° C.), deposition gauge readings(Å/sec), and current vacuum pressure (torr) are documented. Power issupplied to the E-beam apparatus. It is possible to raise the power tothe gun in increments of 0.1%. The power is raised to a point just belowevaporation and allowed to soak or condition. After soaking, the poweris raised until the desired deposition rate is achieved then a shutteris opened and the polymer coated wire mechanism is set to the desiredrate and deposition of polymer begins. The rotation of the drum isstarted. At the end of the trial, the E-beam shutter is closed, the drumrotation is stopped, the power is disconnected from the E-beam, thetube, block heater and wire feed is turned off. After a cool downperiod, the chamber is opened to atmosphere. The coated material isremoved.

Appendix Example 30 Example Drum with Vapor Tube and E-Beam (Wire Feed)

Release Styron Support Aluminum Material Material Supplier Dow SupplierMat. Research Corp. No. 685D No. 90101E-AL000-30002 PVD Conditions:Release E-Beam Thickness Support Drum Wire Coat Wire Power (Angstroms)Thickness Speed Revolutions Size Weight Speed 20% 200 150 1 RPM 1000.005 in./ 0.0005 gms/in 6 Angstroms dia

The following construction was made at the conditions shown above: 48gauge polyester wrapped around the drum for easy removal was polymerrelease coated with styrene and metallized in the Temiscal electron beammetallizer with aluminum. The polyester film was removed from themetallizer and run through a laboratory releasing device using acetoneto separate the aluminum from the releasing layers and the polyesterfilm. The aluminum and acetone solution was then decanted andcentrifuged to concentrate the flakes. The resulting flakes were drawndown on a slide and microphotographed on an Image Pro Plus ImageAnalyzer from Media Cybernetics. The flakes in solution were thenreduced in particle size using an IKA Ultra Turex T50 Homogenizer. Aparticle size distribution was taken on the resulting flake using aHoriba LA 910 laser scattering particle size distribution analyzer. Thefinished particle size of the flake was D10=3.3, D50=13.2, D90=31.2.

The photograph at page 30 of the Appensix illustrates:

Aluminum pictured homogenized 30″

Particle size homogenized 30″ in microns: D10=8.21, D50=26.68, D90=65.18

Homogenized 6 minutes 30 seconds.

Finish particle size in microns D10=3.33, D50=13.21, D90=31.32

Example Drum with Vapor Tube and E-Beam (Wire Feed)

Nanoparticles:

Release Styron Support Aluminum Material Material Supplier Dow SupplierMat. Research Corp. No. 685D No. 90101E-AL000-30002 PVD Conditions:Release E-Beam Thickness Support Drum Wire Coat Wire Power (Angstroms)Thickness Speed Revolutions Size Weight Speed 17% 200 3 Angstroms 2.2RPM 100 0.005 in./ 0.0005 gms/in 6 dia

The following construction was made at the conditions shown above: 48gauge polyester wrapped around the drum for easy removal was polymerrelease coated with styrene and metallized in the Temiscal electron beammetallizer with aluminum. The polyester film was removed from themetallizer and run through a laboratory releasing device using acetoneto separate the aluminum from the releasing layers and the polyesterfilm. The resulting aluminum particle slurry was saved in a vial forfurther study.

The goal of the trial was to achieve nanoparticles of aluminum resultingfrom managing the deposition process such that as the aluminum isdeposited on the releasing layer it remains in the island growth state.These islands of uncoalesced aluminum are then coated with releasingmaterial then recoated with islands of aluminum. This is repeated untila 100 multilayer sandwich of release/aluminum islands/release is formed.

Drum with Polymer Block & E-Beam (Melt Pump Extruder)

Referring to FIGS. 17 and 18, a vacuum chamber and heater block similarto those described above is modified to deliver molten polymer(thermoplastic polymer used as a release coat material) to the vacuumchamber. The vacuum chamber includes the rotating drum 168, a depositiongauge, the stainless steel heater block 170, and an electron beam(E-beam) gun 172. The drum is approximately one foot in diameter and sixinches wide on the surface. The drum can be rotated and the speed andnumber of revolutions monitored. The heater block slot is open into acavity running through the center of the block. The block has threeindependent heaters used to control the temperature of the block. Theblock is fed molten polymer by two heated capillary tubes 174 connectedto the polymer crucibles located in each end or the block. These tubesare connected to a melt pump located outside of the chamber. It is fedby a nitrogen blanketed melt vessel 175 containing conditioned polymerand an extruder 176. A deposition gauge placed approximately one inch infront of the slot measures the amount of material passing through theslot in angstroms per second (Å/sec).

To add material, polymer is pumped to cavities in each end of the heaterblock. The drum is covered with PET film. The E-beam gun has four copperhearths on a rotating plate. One hearth at a time is positioned in linewith the E-beam gun. The material to be evaporated is placed directly inthe hearth or in an appropriate crucible liner placed in the hearth atthe proper turret location. A second deposition gauge is located nearthe drum surface, above the crucible. It measures the amount of materialevaporated from the crucible in angstroms per second (Å/sec). Once thisis done, the chamber is closed and the vacuum cycle is started. Thechamber is evacuated until the pressure reaches at least 6×10⁻⁵ torr.Once the desired vacuum is achieved, power to the three heaters isturned on. The heaters are set to ramp up to the desired temperature ina 20 minute interval. Measurements are transmitted to a computer fileapproximately every 6 seconds. The time, block temperature in threezones (° C.), deposition gauge readings (Å/sec), and current vacuumpressure (torr) are documented. Power is supplied to the E-beamapparatus. It is possible to raise the power to the gun in increments of0.1%. The power is raised to a point just below evaporation and allowedto soak or condition. After soaking, the power is raised until thedesired deposition rate is achieved and then a shutter is opened oncethe polymer begins to deposit. Rotation of the drum is started and themelt pump is set to the desired rate. The trial ends if either thedeposition gauge crystal fails or when all of the material has beenevaporated and the deposition gauge reading falls to zero. At the end ofthe trial, the E-beam shutter is closed, drum rotation is stopped, themelt pump is stopped, the power is disconnected from the E-beam, and theblock heater is turned off. After a cool down period, the chamber isopened to atmosphere. The coated material is removed.

Release-Coated Carrier Film Process

In one embodiment, the present invention can be used for manufacturingrelease-coated polymeric carrier film such as release-coated polyester(PET). Referring to FIG. 19, a polyester carrier film 180 is wrappedaround a rotating cooling drum 182 contained in a vacuum chamber 184.The film passes from a film unwind station 186 around approximately 300°or more of surface area of the rotating cooling drum, and the coatedfilm is then taken up at a film rewind station 188. A polymer deliverysource 190 directs the polymer material toward the carrier film and theE-beam 192 gun vaporizes the polymer for coating it onto the carrierfilm. The polymeric coating hardens and is then taken up at the rewindstation. The process provides a thermoplastic polymeric release-coatedheat-resistant polymeric carrier film, in which the film provides goodrelease properties for flake material applied to the film by vapordeposition techniques in a vacuum chamber. The film provides effectiverelease in forming thin flat angstrom level flakes.

Polystyrene Trials

From trials in the electron beam metallizer, it was discovered that theheater block temperature had a significant effect on the condition ofthe polystyrene after it was evaporated and deposited. For all trials,the Dow 685D polystyrene was used as deposition material. This materialhas a molecular weight (MW) of roughly 300,000.

Trials were run with heater block temperatures ranging from 300° C. to375° C. in 25° C. increments. The rate at which the block was heated wasvaried, but did not seem to have as significant effect as the eventualtemperature. All trials were run according to the Drum with BlockProcedure described above.

In the first trial, the block was loaded with 10 pellets of the Dow 685Dpolystyrene. The temperatures on the heaters were set for 300° C. Atthat temperature, there is minimal deposition. Gauge readings rangedfrom 5-10 Å/sec. At the end of the trial there was very little apparentresidue.

In the next trial, the block was set to reach a temperature of 325° C.Deposition increased into the 20-30 Å/sec range. At the end of thetrial, there was a noticeable film deposited. The film was clear incolor and was solid with no tackiness.

Next the block was programmed to reach 350° C. The deposition rates weresimilar to that in the trial to 325° C. At the end of the trial, thefilm was different than the film that was formed in the previous trial.The film in this trial was tackier to the touch and there appeared to bea slight discoloration.

Finally, the block was set for a temperature ramp to 375° C. Depositionrates increased to a rate of nearly 40 Å/sec. At the end of the trial,yellowish oil was left on the film. The oil was easily wiped away, butthere was no sign of clear polystyrene film beneath it.

From these trials it was concluded that above 350° C. polystyrene beginsto degrade. This confirms values that were found in the literature. Attemperatures greater than 350° C., the polystyrene evaporates and thenappears to depolymerize and leave a residue of nearly pure styrenemonomer. This was confirmed by FTIR analysis of the residue.

In further study, samples of the Dow polystyrene were sent to an outsidelab for analysis. A method was devised to determine what was evaporatingfrom the polymer as the temperature was raised to a desired operatingtemperature. Using a “Direct Insertion Probe” method coupled with GC-MSanalysis, the temperature was set to ramp to 325° C. at a rate of 30°C./min. Once the maximum temperature was reached, it was held for 10minutes.

An ion counter in the apparatus indicated when material was beingevaporated from the solid pellet. Two peaks appeared during the trial,one at approximately 260° C. and another at 325° C. GC-MS analysis wasperformed on these two peaks. The first peak showed large concentrationsof low molecular weight species including, but not limited to, monomersand dimers of polystyrene. The second peak does not show nearly as manyvolatiles in its GC-MS analysis. From this analysis it was concludedthat upon first heating, a large quantity of unpolymerized material andmany other low molecular weight volatiles are liberated from the bulkpolystyrene. After prolonged heating, the desired polymer is evaporatedand deposited onto the desired surface. I was concluded that for optimumperformance, the bulk polymer needs to be preheated or otherwiseconditioned to remove as much “low end” material as possible.

In another experiment, we used the same Direct Insertion Probe method totry to gain further insight into what, is happening in the first peakseen in the first experiment. In this trial the applied heat was rampedup to 260° C. and held the temperature. This is where the peak appearedin the first trial. The purpose was to characterize what was beingevaporated at this point by GC-MS and also see if the material could beremoved from the bulk material by a preheating step.

The peak appeared in approximately the same place and GC-MS showed alarge assortment of low molecular weight species. These included sometrace of the styrene monomer, but there were numerous other organicfragments present. After a period of about 10-12 minutes, the peak haddisappeared. This indicated that the volatile material had been removedfrom the bulk material and a strategy of preheating should be effectivein forming clean polymer films. From this series of tests new procedureswere developed to increase the effectiveness of depositing polystyrenefilm with the Dow 685D polymer. First, the bulk material is heated to atemperature of 260-300° C. During this preheating, the film should becovered so as not to allow the low end products to reach the web. Thisstep may also be done outside the vacuum or at least outside of thedeposition chamber so that contamination can be minimized. Aftersufficient time, the temperature should then be raised to 325° C. Thistemperature provides the highest deposition rate without causingdegradation of the polystyrene.

Further observations came from running similar experiments with otherpolystyrene samples. In this case we used a 4,000 MW and a 290,000 MWpolystyrene supplied by Pressure Chemical. These samples are polystyrenestandards and have very narrow molecular weight distributions. They arealso free of most contaminants that would be found in most commercialpolymers. From these experiments we made the following conclusions. Theuse of the 4,000 MW material has less of an impact on the vacuumpressure than the 290,000 MW material. The pressure rises more when thehigher molecular weight material is used. This is consistent with datawe found during trials in the bell jar. We also observed that the290,000 MW material began deposition at a lower temperature than the4,000 MW material. We confirmed this by running TGAs on both materials.The TGAs showed that the 4,000 MW material does indeed show a weightloss beginning at a higher temperature than that observed for the290,000 MW polymer.

Polymer Conditioning

Before the polymer can be used in a deposition process, it must beconditioned to remove moisture and low molecular weight material fromthe bulk polymer. Using the Dow 685D polystyrene, we accomplished thisin a two stage conditioning process. In the first stage, a quantity ofthe polystyrene is placed in a vacuum oven and held at 225° C. for 16hours. This temperature is high enough to drive off most moisture in thepolymer. This temperature is also chosen because it is below the pointwhere polymer degradation is seen. In trials run at 275° C., thepolystyrene sample showed significant degradation after the 16 hourconditioning period. After the conditioning period, the polymer isremoved and placed in a desiccator so that it does not take on anymoisture while it is cooling.

The second stage of the conditioning is done when the polymer is readyto be used in the metallizer. It is removed from the desiccator andimmediately placed in the metallizer so that, moisture gain isminimized. Before deposition begins, the polymer block containing thefirst stage conditioned polymer is heated to 275° C. and held at thattemperature for 20 minutes. At this temperature, any remaining moistureis driven off and the low molecular weight material in the polymer isalso removed. This low molecular weight material will include unreactedmonomer and many other impurities found in the bulk polystyrene. Afterholding at 275° C. for the necessary conditioning time, the polymershould be ready for deposition.

By utilizing this two stage conditioning process, the final film shouldbe of a consistent molecular weight and it should also be free of mostlow molecular weight impurities. This should provide for a much moreconsistent and reliable film.

Reuse of Solvent & Polymer

When the current release coat is stripped and the flake is collected thespent solvent along with the dissolved release coat is sent through adistillation process to reclaim the solvent. When the solvent isreclaimed the still bottoms are sent out to be disposed of as hazardouswaste. In this experiment we attempted to reuse the still bottoms as arelease coat. The still bottoms as collected were 24% NVM. This materialwas reduced to 8.3% NVM with three parts IPAC and one part NPAC. Thislacquer was than drawn down on 2 mil polyester using a #2 Meyer rod. Theresulting coating was clear with a coat weight of 0.3 grams per metersquare. The draw down was than metallized with aluminum in the bell jarmetallizer. The resulting aluminum layer had an optical density of 2 to2.5 as measured on the Macbeth densitometer.

The resulting construction was than dissolved in acetone taking 30seconds to release from the polyester. The flake was than drawn down ona slide and analyzed. Flake produced by this method was in the 400 to600 micron range with a smooth surface and was indistinguishable fromthe current product.

Wire Coating

FIG. 20 illustrates a wire coating apparatus for coating polymer ontothe wire used in the wire feed embodiments described previously.

Materials:

A mixture of fully dissolved Dow 685 polystryene polymer in xylene.

Dow 685 45 pts by wt

Xylene 55 pts by wt

Bare Nickel/Chromium wire 0.005 inch in gage from ConsolidatedElectronic Wire and Cable.

Description of Apparatus:

Referring to FIG. 20, the coating apparatus consists of four sections:unwind 200, coating body 202, drying tube 204, and winder 206. The spoolof wire is restricted in side to side movement while allowing it tounwind with a minimum of resistance. The coating body comprises asyringe body 208, Becton Dickson 5 cc disposable syringe, and a syringeneedle 210, Becton Dickson 20GI Precision Glide needle. The disposablesyringe is filled with the coating mixture and the needle meters a givenamount of material onto the wire. The drying tube is constructed fromcopper plumbing tubing. From top to bottom the tube consists of a 1/2inch tube 212 six inches long, a ½ to ¾ reducer 214, a ¾ inch tube 216two inches long, a ¾ inch tee 218 from which a 4 inch ¾ inch tube 220extends perpendicularly. An exhaust fan 222 is attached to this pipedrawing air from the apparatus. The straight section of the tee isattached to a ¾ inch copper tube 224 five feet long. This section is thedrying section of the apparatus. Another ¾ inch tee 226 is attached tothe 5 foot section. The perpendicular tee is attached to a three inch ¾inch tube 228 connected to a 90 degree elbow 230 turned upwards. To thiselbow is attached a 1½ inch tube 232 and a ¾ inch threaded connector234. This connector is attached to a two inch to ¾ inch black ironreducer. A two inch pipe 236 five inches long is screwed into thisreducer. The two inch pipe holds the barrel of the hot air gun. Thevertical section of the tee is attached to a two inch ¾ inch tube 238,then reduced at 240 to ½ inch. A final six inch section of ½ inch tubing242 is attached.

Description of Coating Application:

Using the apparatus displayed above the coating is applied to the wire.The wire is unwound from the spool and fed though a syringe body thatcontains the mixture of polystyrene polymer and solvent. As the wire isdrawn down the syringe body through the syringe needle the wire iscovered with the mixture. The coated wire is fed through a copper tubethrough which heated air is passed. Air is drawn from an exit port inthe top of the tube at a rate greater than heated air is supplied from aport in the bottom of the tube. The extra air required by the exhaustport is supplied at the ends of the tube where the wire enters andexits. The amount of hot air supplied to the tube was controlled throughthe use of a rheostat. It was found 85% of full output was the preferredtemperature. Greater temperature caused the coating to blister, lesstemperature detracted from drying. The wire was wound on a spool afterpassing through the drying tube. The desired feed rate of the wire was22 inches per minute through the drying tube. The speed of the windingspool was controlled manually using another rheostat. As more wire waswound onto the spool the rheostat setting was dropped to compensate forthe faster pull of the wire during winding. Final coating on the wirewas in the 0.4 to 0.5 mg/inch range.

DOW STYRON 685D Sample Preparation and Analysis:

About 75 milligrams of the polystyrene resin from each plastic containerwas separately dissolved in 10 mL of tetrahydrofuran (THF) and tumbledfor about 3 hours. Each THF solution was filtered through 0.45 μm PTFEfilter and placed in an autosampler vial.

The GPC instrument was a Waters 2690 pumping system with a Waters 410refractive index detector. The columns were three Plgel Mixed-C 300mm×7.5 from Polymer Labs. The mobile phase was THF at 1.0 mL/min. Theinjection size was 50 μL. Calibration was against a set of twelvepolystyrene standards obtained from Polymer Labs, ranging from 580 to1,290,000 Da. Millennium version 3.2 software from Waters was used withthe GPC option. Calibration was done daily and a check sample of SRM 706polystyrene from the National Institute for Standards and Technology wasalso analyzed daily with each batch of samples.

Results:

The calculated value for the molecular weight distribution of thesoluble polymer portion of the sample is shown in the following table.The values for the peak molecular weight (Mp), number average molecularweight (Mn) and weight average molecular weight (Mw) are expressed asthousands to give the correct number of significant figures. Qualitycontrol data indicate that a relative difference of ten percent for Mnand five percent for Mw are not significant.

Sample Mp Mn Mw Dispersity STYRON 685D 266k 107k 313k 2.94 STYRON 685Dduplicate 272k 138k 320k 2.32 STYRON 685D average 269k 123k 317k 2.63Polystyrene Polymer Characterization Data from Pressure Chemical Co.

Nominal 290,000 MW Styrene By Lalls: M_(w) = 287,000 By Size ExclusionChromatography M_(w) = 288,800 1 × 60 cm Plge1 5 micron mixed gel M_(n)= 274,600 THF @ 1 ml/min. 20 ml. @ 0.02% M_(p) = 293,000 By IntrinsicViscosity: M_(y) = 288,800 Toluene @ 30° C. M_(v) calculated from (h) =12 × 10 − ⁵M⁰.71 (h) = 0.904 Nominal 4,000 MW Styrene By Vapor PressureOsmometer: M_(n) + 3,957 THF, 38 C., four concentrations 08 membrane BySize Exclusion Chromatography: M_(w) = 4,136 M_(n) = 3,967 M_(p) = 4,000By Intrinsic Viscosity: M_(v) = 4,075 THF @ 30° C. M_(v) calculated from(h) = 1.71 × 10 − ³M_(v).712 (h) = 0.06

Preparation of Dried Nanoscale and Angstrom Scale Particles:

The method of washing residual release coating from the flake after itis removed from the drum or carrier is as follows. Using a BuchnerFunnel with a 4,000 Ml. capacity and a side outlet for vacuum filteringand a filter such as a Whatman microfiber filter both available fromFisher Scientific. First add flake to the funnel with the filter inplace and the vacuum on. Wash the flake by rinsing with the appropriatesolvent. The solvent used may be Acetone, Ethyl Acetate or an Alcoholdepending on the solubility of the release coat. The flake should bewashed until the residual release coat is removed or reduced to thedesired level. The filtered material may then be baked to eliminatevolatile materials. This filter cake may also be annealed by baking at ahigher temperature. The spent solvent may be distilled to be reclaimedand reused. The still bottoms may be reclaimed and reused in the releasecoating as mentioned previously. In production, larger vacuum filteringdevices are available.

Barrier Materials

Experiments were run to determine the effect of flake size,pigment-to-binder ratio and coat weight on the moisture vaportransmission rate (MVTR) and oxygen permeability of flake-containingfilms. Large flake size was 20 microns and small flake size was 12microns.

MVTR test data were as follows:

Flake Size P.B. Coat Weight (g/m²) MVTR/(g/m²-day) Large 3:1 3.14 4.86Large 1:1 3.62 5.85 Small 3:1 3.18 1.82 Small 3:1 0.8 8.86 Large 3:10.74 15.0 Large 3:1 3.14 4.86 Large 3:1 3.14 4.86 Small 3:1 3.18 1.82Large 1:1 3.62 5.85 Large 1:1 1.38 11.90 Clear Vehicle 1.08 74.4 DartekSF - 502 Nylon Film 58.3 Pigment: Aluminum Flakes Binder: Cellulose inkvehicle

Further test data revealed an MVTR of 1.2 for small particles, a 5:1pigment-to-binder ratio and a coat weight of 5 μm/m².

The data show that additions of properly selected flakes can have adramatic effect on MVTR. For example, the table shows a decrease of theMVTR of a nylon film from 75 g/m²-day to 1.8 g/m²-day with the bestconditions being high P:B, small particle size (such as the angstromscale flakes of this invention) and high coat weight. The further testdata shows even better results.

Based on these data, applications for angstrom scale particles(thickness of less than about 100 angstroms and particles size of lessthan about 20 microns) for example, may include moisture transmissionbarrier materials. In use, the flakes line up in parallel in anessentially common plane and produce barriers to water molecules passingthrough the flake-containing film. Flakes, such as glass flakes, forexample, can be used in polymeric films such as PVC, to inhibitplasticizer migration.

Electrical Applications

By running the release-coated carrier at a high rate of speed, depositedmetal such as aluminum will produce discrete islands (nano-particlesdescribed above). These particles (when removed from the release layer)can be blended in a flake containing film, or used as-is in a polymericfilm. The nano-particle containing film can increase electricalcapacitance. Capacitance is proportional to dielectric constant and areaand inversely proportioned to the separation distance between thecapacitor plates. Nano-particles dispersed between larger particle sizeflakes raise the dielectric constant and therefore the capacitance.

Other uses of nanoparticles are described in Handbook of DepositionTechnologies for Films and Coatings, “Nucleation, Film Growth, andMicrostructural Evolution,” Joseph Green, Noyes Publication (1994).

1. A method for using nanoscale flakes produced by a process comprising:providing a vacuum deposition chamber containing a deposition surface;providing a release coat source and a flake deposition source in thevacuum deposition chamber, each directed toward the deposition surface;depositing on the deposition surface under vacuum in alternating layersa vaporized polymeric release coat layer from the release coat sourceand vapor deposited discrete islands of flake material from the flakedeposition source to build up in sequence a multi-layer vapor deposit offlake material layers comprising discrete islands of the flake materialseparated by and deposited on corresponding intervening release coatlayers; the release coat layers comprising a polymeric material whichwas vaporized under vacuum to form a smooth continuous solvent solubleand dissolvable barrier layer and support surface on which each of thelayers of flake material is formed; removing the multi-layer vapordeposit from the vacuum deposition chamber and separating it intonanoscale flake particles by treatment with a solvent which dissolvesthe release coat layers and yields flakes with smooth, flat surfaceswhich are essentially free of the release coat material; and wherein thenanoscale flakes are used by incorporation of the nanoscale flakes intobarrier films, catalytic materials, optically reflective flakes;coatings to reflect, scatter or absorb light; structural materials toimprove mechanical properties; polymeric films; and into materials andcoatings for imparting electrical properties.
 2. The method according toclaim 1 in which the flake layer comprises a vapor-deposited materialselected from the group consisting of metal in elemental form, aninorganic material, and a non-metal.
 3. The method according to claim 2in which the non-metal comprises silicon monoxide, silicon dioxide or apolymeric material, in which the inorganic material is selected from thegroup consisting of magnesium fluoride, silicon monoxide, silicondioxide, aluminum oxide, aluminum fluoride, indium tin oxide, titaniumdioxide and zinc sulfide, and in which the metal is selected from thegroup consisting of aluminum, copper, silver, chromium, indium,nichrome, tin and zinc.
 4. The method according to claim 1 in which therelease coat material is selected from styrene or acrylic polymers orblends thereof.
 5. The method according to claim 1 in which the flakelayers are deposited to a flake (discrete island) thickness of less thanabout 100 nanometers.
 6. The method according to claim 1 in which therelease coat layer comprises a thermoplastic polymeric material.
 7. Themethod according to claim 1 in which the release coat layer comprises alightly cross-linked resinous material which is dissolvable in anorganic solvent to yield the flakes which are essentially free of therelease material.
 8. The method according to claim 1 in which therelease coat layers are dissolvable in an organic solvent.
 9. A methodaccording to claim 1 wherein the release coat source comprises a wirefeed mechanism in which the polymeric release coat material is coatedonto a wire fed to the vacuum chamber and evaporated under heat thereinto be deposited as said release coat layer.
 10. The method according toclaim 9 in which the release coat layer is selected from styrene oracrylic polymers or blends thereof.
 11. The method according to claim 9in which the wire feed mechanism delivers coated release coat materialto a heater block positioned adjacent the deposition surface forevaporating the release coat material.